Methods and devices for growing scintillation crystals with short decay time

ABSTRACT

The present disclosure discloses a method for growing a crystal with a short decay time. According to the method, a new single crystal furnace and a temperature field device are adapted and a process, a ration of reactants, and growth parameters are adjusted and/or optimized, accordingly, a crystal with a short decay time, a high luminous intensity, and a high luminous efficiency can be grown without a co-doping operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2019/101725 filed on Aug. 21, 2019, the entire contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to the field of crystal growth,and in particular, to methods and devices for growing scintillationcrystals with short decay time.

BACKGROUND

Scintillation crystal is used as an energy conversion medium that canconvert ionizing radiation energy (e.g., a gamma-ray, an X-ray) intolight energy (e.g., visible light). The scintillation crystal (e.g.,LSO, LYSO, BGO, BSO, GSO) is widely used in nuclear medicine field suchas X-ray tomography (CT), positron emission tomography (PET), nucleardetection field such as industrial tomography (e.g., industrial CT), oilwell exploration field, nuclear physics field, high-energy physicsfield, an environmental detection field, safety monitoring field, weaponfire control and guidance field, etc. In order to decrease a decay timeof the scintillation crystal, some divalent or trivalent non-rare earthcations (e.g., Mg, Ca, Zn, Yb, Dy, Pb, Tb, Li, Na) may be co-doped intothe crystal during the crystal growth. In this case, a lattice constantand a segregation coefficient of Ce in the crystal may be changed byintroducing a lattice distortion, thereby affecting an energy bandstructure of luminescent ions and improving the efficiency and speed ofcapturing high-energy photons and converting them into visible light bythe luminescent ions. However, the co-doped divalent or trivalentnon-rare earth cations introduced into the crystal may affect the lightyield of the crystal. In addition, the co-doped bivalent or trivalentnon-rare earth cations may not be uniformly distributed in the crystal,which may cause a non-uniform distribution of light yield and decay timeof the crystal and increase the cost of crystal production andscreening.

SUMMARY

The present disclosure discloses a method for crystal growth. The methodfor crystal growth decreases a decay time of the crystal bypreprocessing a valence and/or ration of luminescent ions in reactants.The method may not dope any co-doped element into the crystal, which mayaffect a light yield of the crystal.

According to an aspect of the present disclosure, a crystal is provided.A formula of the crystal may be

${X_{2x}\text{:}M_{2m}\text{:}{Lu}_{2{({1 - x - m - z})}}Y_{2z}{SiQ}_{({5 - \frac{n}{2}})}N_{n}},$where X may consist of at least one of Ce, Cl, F, Br, N, P, or S, M mayconsist of at least one of Ca, Mg, Sr, Mn, Ba, Al, Fe, Re, La, Ce, Rr,Nd, Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, Yb, Tm, Lu, Sc, or Y, Q may consistof at least one of O, Cl, F, Br, or S, N may consist of at least one ofCl, F, Br, or S, and x=0.000001-0.06, m=0-0.006, z=0-1, and n=0-5.

In some embodiments, X may consist of Lu, M consists of Ce, and Q mayconsist of O, and the formula of the crystal may be

${{Lu}_{2{({1 - m})}}{Ce}_{2m}{SiO}_{({5 - \frac{n}{2}})}N_{n}},{{or}\mspace{14mu}{Lu}_{2{({1 - z - m})}}Y_{2z}{Ce}_{2m}{SiO}_{({5 - \frac{n}{2}})}{N_{n}.}}$

According to another aspect of the present disclosure, a method forgrowing a crystal is provided. A formula of the crystal may be

${X_{2x}\text{:}M_{2m}\text{:}{Lu}_{2{({1 - x - m - z})}}Y_{2z}{SiQ}_{({5 - \frac{n}{2}})}N_{n}},$where X may consist of at least one of Ce, Cl, F, Br, N, P, or S, M mayconsist of at least one of Ca, Mg, Sr, Mn, Ba, Al, Fe, Re, La, Ce, Rr,Nd, Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, Yb, Tm, Lu, Sc, or Y, Q may consistof at least one of O, Cl, F, Br, or S, and N may consist of at least oneof Cl, F, Br, or S. The method may include weighting reactants accordingto a molar ratio of the reactants according to a reaction equation forgenerating the crystal after a first preprocessing operation isperformed on the reactants, wherein x=0.000001-0.06, m=0-0.06, z=0-1,and n=0-5. The method may include placing reactants on which a secondpreprocessing operation has been performed into a crystal growth deviceafter an assembly processing operation is performed on at least onecomponent of the crystal growth device. The at least one component ofthe crystal growth device may include a crucible. The assemblyprocessing operation may include at least one of a coating operation, anacid soaking and cleaning operation, or an impurity cleaning operation.The method may include introducing a flowing gas into the crystal growthdevice after sealing the crystal growth device. The method may alsoactivate the crystal growth device to grow the crystal based on theCzochralski technique.

In some embodiments, X may at least consist of Ce, and a reactantconsisting of Ce may include at least one of CeO₂, Ce₂O₃, Ce(CO₃)₂,CeCl₃, cerium fluoride, cerium(III) sulfate, or cerium(III) bromide.

In some embodiments, a weight of a reactant consisting of Si may excessof 0.01 at %˜10 at %, 0.1 at %˜10 at %, 1 at %˜10 at %, 2 at %˜9 at %,or 4 at %˜7 at %.

According to yet another aspect of the present disclosure, a method forgrowing a crystal is provided. The method may include weightingreactants based on a molar ratio of the reactants according to areaction equation (1) or a reaction equation (2) after a firstpreprocessing operation is performed on the reactants:(1−x−y)Lu₂O₃+SiO₂+2xCeO₂ +yCe₂O₃→Lu_(2(1-x-y))Ce_(2(x+y))SiO₅+x/2O₂↑  (1)(1−x−y−z)Lu₂O₃ +zY₂O₃+SiO₂+2xCeO₂+yCe₂O₃→Lu_(2(1-x-y-z))Y_(2z)Ce_(2(x+y))SiO₅ +x/2O₂↑  (2)where x=0.0001%˜6%, m=0˜6%, z=0˜1, and a weight of SiO₂ may excess of0.001%˜10% of its weight. The method may include placing reactants onwhich a second preprocessing operation has been performed into a crystalgrowth device after an assembly preprocessing operation is performed onat least one component of the crystal growth device. The at least onecomponent of the crystal growth device may include a crucible, and theassembly processing operation may include at least one of a coatingoperation, an acid soaking and cleaning operation, or an impuritycleaning operation. The method may include introducing a flowing gasinto the crystal growth device after sealing the crystal growth device.The method may also include activating the crystal growth device to growthe crystal based on the Czochralski technique.

In some embodiments, a weight of SiO₂ may excess of 0.01%˜10%, 0.1%˜10%,1%˜10%, 2%˜9%, or 4%˜7% of its weight.

In some embodiments, x=0.001%˜6%, 0.01%˜6%, 0.15%˜6%, 1%˜6%, or 2%˜5%.

In some embodiments, y=1%˜5%, 2%˜4%, 2.5%˜3.5%, or 2.8%˜3.2%.

In some embodiments, a purity of each of the reactants may be greaterthan 99%, 99.9%, 99.99%, or 99.999%.

In some embodiments, the first preprocessing operation may include aroasting operation under 800° C.˜1400° C. The second preprocessingoperation may include at least one of an ingredient mixing operation ora pressing operation at room temperature.

In some embodiments, the flowing gas may include oxygen or a mixed gasof oxygen and one or more of nitrogen and inert gas. When the flowinggas is a mixed gas of oxygen and one or more of nitrogen and inert gas,a volume ratio of oxygen may be 0.001%˜10% in an initial stage of thecrystal growth.

In some embodiments, a flow rate of the flowing gas may be 0.01 L/min˜50L/min.

In some embodiments, a purity of the flowing gas may be greater than99%, 99.9%, 99.99%, or 99.999%.

In some embodiments, a melting time of a heat treatment for melting thereactants may be 5 hours˜48 hours during the crystal growth.

In some embodiments, a distance between a seed crystal and an uppersurface of the reactants may be 5˜100 mm during melting the reactantsduring the crystal growth.

In some embodiments, the method may include sinking the seed crystal to0.1 mm˜50 mm below a surface of a melt of the reactants by controlling apulling rod during temperature adjustment.

In some embodiments, the method may further include maintaining aconstant temperature at 1950° C.˜2150° C. for at least 0.1 hours˜1 hourafter temperature adjustment.

In some embodiments, a rotation rate of a pulling rod may be 0.01r/min˜35 r/min during the crystal growth.

In some embodiments, a growth rate of the crystal may be 0.01 mm/h˜6mm/h during the crystal growth.

In some embodiments, a temperature decreasing time of the crystal duringthe crystal growth may be 20 hours˜100 hours.

In some embodiments, during a shouldering process of the crystal growth,a shoulder angle may be 30 degrees˜70 degrees, and a shoulder length maybe 40 mm˜130 mm.

In some embodiments, during an ending process of the crystal growth, anending angle may be 30 degrees˜70 degrees, and an ending length may be40 mm˜110 mm.

In some embodiments, for the flowing gas including the mixed gas ofoxygen and one or more of nitrogen or inert gas, during a coolingprocess of the crystal growth, the volume ratio of oxygen in the flowinggas may be 1%˜30% when a temperature is within 1400° C.˜800° C. Thevolume ratio of oxygen in the flowing gas may be 0.001%˜20% when thetemperature is lower than 800° C.

In some embodiments, the crystal growth may be controlled by aproportional integralderivative (PID) controller. A PID parameter may be0.1˜5.

According to yet another aspect of the present disclosure, a device forgrowing a crystal is provided. The device may include a temperaturefield device. The temperature field device may include a bottom plate, acover plate, a drum, and a filler. The bottom plate may be mounted at abottom of the temperature field device and cove an open end of the drum.The cover plate may be mounted at a top of the temperature field deviceand cover another open end of the drum. The filler may be filled in thedrum.

According to yet another aspect of the present disclosure, a device forgrowing a crystal is provided. The device may include a temperaturefield device. The temperature field device may include a bottom plate, acover plate, a first drum, a second drum, and a filler. The bottom platemay be mounted at a bottom of the temperature field device and covers anopen end of the first drum. The cover plate may be mounted at a top ofthe temperature field device and covers another open end of the firstdrum. The second drum may be mounted within the first drum. The fillermay be filled in the second drum, and/or a space between the first drumand the second drum.

In some embodiments, the filler filled in the second drum may be atleast configured to support a crucible and cover at least a portion ofthe crucible. Reactants used for growing the crystal may be placed inthe crucible to react.

In some embodiments, the temperature field device may further include aheater. The heater may be mounted above the crucible.

In some embodiments, the first drum may be made of heat resistantmaterial.

In some embodiments, a shape of the filler may include at least one of agranular, a brick, or a felt. The filler may be made of the heatresistant material.

In some embodiments, a particle size of the filler may be 5˜200 mesh.

In some embodiments, an amount and/or a tightness of the filler may beadjusted according to a condition of the crystal growth.

In some embodiments, a filling height of the filler may result in that avertical distance between an upper edge of the crucible supported by thefiller and an upper edge of an induction coil mounted outside thetemperature field device is 0 mm˜∓50 mm, wherein “−” represents that theupper edge of the crucible is lower than an upper edge of the inductioncoil, and “+” represents that the upper edge of the crucible is higherthan the upper edge of the induction coil.

In some embodiments, the heater may be made of one or more of iridium,platinum, molybdenum, tungsten, graphite, or a material which has a highmelting point and can be heated by electromagnetic induction. An innerdiameter of the heater may be 40 mm˜240 mm and a height of the heatermay be 2 mm˜200 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. These exemplary embodiments are described in detail withreference to the drawings. These embodiments are non-limiting exemplaryembodiments, in which like reference numerals represent similarstructures throughout the several views of the drawings, and wherein:

FIG. 1 is a flowchart illustrating an exemplary method for growing acrystal according to some embodiments of the present disclosure;

FIG. 2 is a schematic diagram illustrating an exemplary temperaturefield device according to some embodiments of the present disclosure;

FIG. 3 is a schematic diagram illustrating a top view of a cross-sectionof an exemplary temperature field device according to some embodimentsof the present disclosure;

FIG. 4 is a schematic diagram illustrating a top view of an exemplaryfirst cover plate according to some embodiments of the presentdisclosure;

FIG. 5 is a schematic diagram illustrating an exemplary observation unitaccording to some embodiments of the present disclosure; and

FIG. 6 is a schematic diagram illustrating an exemplary image of a growncrystal according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details withreference to the accompanying drawings are set forth by way of examplesin order to provide a thorough understanding of the relevant disclosure.Various modifications to the disclosed embodiments will be readilyapparent to those skilled in the art, and the general principles definedherein may be applied to other embodiments and applications withoutdeparting from the spirit and scope of the present disclosure. Theidentical numerals in the drawings represent same or similar structuresor operation, unless the context clearly indicates otherwise.

It will be understood that the term “system,” “device,” “unit,” and/or“module,” used herein are one method to distinguish differentcomponents, elements, parts, section or assembly of different level inascending order. However, the terms may be displaced by anotherexpression if they achieve the same purpose.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise,”“comprises,” and/or “comprising,” “include,” “includes,” and/or“including,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

The range of values used herein in the present disclosure brieflyillustrate each value in the range of values.

The flowcharts used in the present disclosure illustrate operations thatsystems implement according to some embodiments of the presentdisclosure. It should be noted that the foregoing or the followingoperations may not be performed in the order accurately. Instead, thesteps can be processed in reverse order or simultaneously. Besides, oneor more other operations may be added to the flow charts, or one or moreoperations may be omitted from the flow chart.

Some embodiments of the present disclosure disclose a crystal. In someembodiments, a formula of the crystal may be

${X_{2x}\text{:}M_{2m}\text{:}{Lu}_{2{({1 - x - m - z})}}Y_{2z}{SiQ}_{({5 - \frac{n}{2}})}N_{n}},$wherein X may consist of at least one of Ce, Cl, F, Br, N, P, or S, Mmay consist of at least one of Ca, Mg, Sr, Mn, Ba, Al, Fe, Re, La, Ce,Rr, Nd, Pm, Sm, Eu, Gd, Td, Dy, HO, Er, Yb, Tm, Lu, Sc, or Y, Z mayconsist of at least one of Sc, Y, Gd, or Lu, Q may consist of at leastone of O, Cl, F, Br, or S, and N may consist of at least one of Cl, F,Br, or S. In some embodiments, when X and/or M consist of two or moreelements, the crystal may be regarded as a doped crystal. Specifically,when X consists of Ce, the crystal may be regarded as Cerium-dopedLutetium oxyorthosilicate crystal or Cerium-doped Lutetium(-yttrium)oxyorthosilicate crystal, which may be used as a practical scintillationcrystal. In some embodiments, a reactant consisting of Ce may includeCeO₂, Ce₂O₃, Ce(CO₃)₂, CeCl₃, cerium fluoride, cerium(III) sulfate, orcerium(III) bromide, or the like, or any combination thereof. In someembodiments, X may consist of Lu, M may consist of Ce, and Q may consistof O. In this case, the formula of the crystal may be

${{Lu}_{2{({1 - m})}}{Ce}_{2m}{SiO}_{({5 - \frac{n}{2}})}N_{n}},{{or}\mspace{14mu}{Lu}_{2{({1 - z - m})}}Y_{2z}{Ce}_{2m}{SiO}_{({5 - \frac{n}{2}})}{N_{n}.}}$In some embodiments, a value of x may be 0.000001˜0.06. The value of xmay be 0.00001 and 0.06. The value of x may be 0.0001˜0.06. The value ofx may be 0.001˜0.06. The value of x may be 0.01˜0.06. The value of x maybe 0.02˜0.05. The value of x may be 0.03˜0.04. The value of x may be0.031˜0.039. The value of x may be 0.032˜0.038. The value of x may be0.033˜0.037. The value of x may be 0.034˜0.036. In some embodiments, avalue of m may be 0˜0.006. The value of m may be 0.001˜0.006. The valueof m may be 0.002˜0.005. The value of m may be 0.003˜0.004. The value ofm may be 0.0031˜0.0039. The value of m may be 0.0032˜0.0038. The valueof m may be 0.0033˜0.0037. The value of m may be 0.0034˜0.0036. In someembodiments, a value of z may be 0˜1. The value of z may be 0.1˜0.9. Thevalue of z may be 0.2˜0.8. The value of z may be 0.3˜0.7. The value of zmay be 0.4˜0.6. The value of z may be 0.42˜0.58. The value of z may be0.44˜0.56. The value of z may be 0.46˜0.54. The value of z may be0.48˜0.52. The value of z may be 0.49˜0.51. In some embodiments, a valueof n may be 0˜5. The value of n may be 0.1˜5. The value of n may be0.5˜4.5. The value of n may be 1˜4. The value of n may be 1.5˜3.5. Thevalue of n may be 2˜3. The value of n may be 2.2˜2.8. The value of n maybe 2.4˜2.6.

In some embodiments, the crystal may be prepared according to thefollowing method.

In a first step, reactants may be weighted based on a molar ratio of thereactants according to a reaction equation for generating the crystalafter a first preprocessing operation is performed on the reactants. Insome embodiments, the crystal may be grown from a melt of a mixture ofan oxide of X, an oxide of M, and an oxide of Si. The reaction equationmay include oxide reactants used for growing the crystal. In order toremove substances such as water and/or organic substance(s) of metalelement(s) to improve the purity of the reactants, the firstpreprocessing operation may be performed on the reactants. For example,a roasting operation may be used to remove water and/or the organicsubstance(s). The roasting operation may be performed using acommercially available high-temperature roasting device such as a mufflefurnace. In some embodiments, a roasting temperature of the reactantsmay be 800° C.˜1400° C. Preferably, the roasting temperature of thereactants may be 900° C.˜1300° C. More preferably, the roastingtemperature of the reactants may be 1000° C.˜1200° C. More preferably,the roasting temperature of the reactants may be 1050° C.˜1150° C. Morepreferably, the roasting temperature of the reactants may be 1060°C.˜1140° C. More preferably, the roasting temperature of the reactantsmay be 1070° C.˜1130° C. More preferably, the roasting temperature ofthe reactants may be 1080° C.˜1120° C. More preferably, the roastingtemperature of the reactants may be 1090° C.˜1110° C. According to thecharacteristics of the different reactants, the time of thehigh-temperature roasting may be not less than 5 hours.

For crystals with different molecular formulas, different weightingmanners may be used for weighting the reactants. In some embodiments,when weighing the reactant(s), a weight of a reactant containing Si mayexcess its weight or a total weight of reactants by 0.01%˜10%. Theweight of the reactant containing Si may excess its weight or a totalweight of reactants by 0.1%˜10%. The weight of the reactant containingSi may excess its weight or a total weight of reactants by 1%˜10%. Theweight of the reactant containing Si may excess its weight or a totalweight of reactants by 2%˜9%. The weight of the reactant containing Simay excess its weight or a total weight of reactants by 3%˜8%. Theweight of the reactant containing Si may excess its weight or a totalweight of reactants by 4%˜7%. The weight of the reactant containing Simay excess its weight or a total weight of reactants by 5%˜6%.

In a second step, the reactants may be placed into a crystal growthdevice after a second preprocessing operation is performed on thereactants.

In some embodiments, the crystal growth device may include a singlecrystal growth furnace and a temperature field device. A type of thesingle crystal growth furnace may include an open type or a vacuum type,which is not limited in the present disclosure. The temperature fielddevice may be used in the single crystal growth furnace to provide atemperature gradient for the crystal growth, and ensure the stability ofa crystallization process of the crystal. A temperature field with goodsymmetry and stability may avoid problems of cracking and abnormalgrowth during the crystal growth. The temperature field device mayinclude a first hollow column and two cover plates covering two ends ofthe first hollow column, respectively. Specifically, two cover platesmay be connected to the two ends of the first hollow column. Theconnection may include a bonding connection, a welding connection, ariveting connection, a key connection, a bolting connection, a buckleconnection, or the like, or any combination thereof. Alternatively, afirst end of the two ends of the first hollow column may be connected toone cover plate of the two cover plates (e.g., via a detachableconnection), a second end of the two ends may be integrally formed withthe other cover plate, or connected to the other cover plate via anon-detachable connection. A second hollow column with a height lessthan that of the first hollow column may be mounted inside the firsthollow column. A space between the first hollow column and the secondhollow column and/or a space in the second hollow column may be filledwith a substance used for heat preservation. For example, the spacebetween the first hollow column and the second hollow column and thespace in the second hollow column may be filled with the substance. Asanother example, the space between the first hollow column and thesecond hollow column may be filled with a substance used for heatpreservation, and the space in the second hollow column may not befilled with the substance. As a further example, the space between thefirst hollow column and the second hollow column may not be filled withthe substance, and the space in the second hollow column may be filledwith the substance. The substance filled in the second hollow column mayalso be configured to support a crucible used for holding the reactants.In addition, an end of the second hollow column near the cover platemounted on a top of the first hollow column may be connected with a heatpreservation board to further improve the heat preservation effect. Inthis case, the temperature field device described in the presentdisclosure may provide a reaction environment with good heatpreservation performance, stable temperature field gradient, and goodsymmetry due to the hollow columns and the substance used for heatpreservation, which may be beneficial to the crystal growth. Moredescriptions regarding the temperature field device may be foundelsewhere in the present disclosure (e.g., FIGS. 2-5), which are notrepeated herein.

In some embodiments, the at least one component of the crystal growthdevice may include a crucible. In some embodiments, the assemblyprocessing operation may include at least one of a coating operation, anacid soaking and cleaning operation, or an impurity cleaning operationon the crucible. It can be understood that the assembly processingoperation may prevent the crystal from being contaminated by an impurityand improve a purity of the crystal. The coating operation may refer tothat the crucible may be coated after being cleaned. The crucible mayvolatize and/or deform in a high temperature condition. Volatiles mayfloat on a surface of the melt or inside the crystal, which may resultin that the seeding of the crystal growth becomes difficult or wrappingmaterials are introduced into the crystal, and further result in afailure of the crystal growth and that the quality of the crystal may beaffected. In addition, a lower middle part of the crucible may deformdue to a hydraulic pressure caused by a melt with high-density meltingpoint under the high temperature condition, which may affect thetemperature gradient of the crystal growth, and in severe case, maycause a crack and leakage of the crucible, and further result in afailure of the crystal growth and that the quality of the crystal may beaffected. Therefore, it is necessary to coat the crucible to reduce thevolatilization and deformation of the crucible. The coating may includea high temperature resistant material, such as Y₂O₃, ZrO₂, etc. The acidsoaking and cleaning operation may refer to soaking an inner wall of thecrucible with an acid with a certain concentration (e.g., 1%˜15%) for acertain period (e.g., 2 hours) after the coating operation. In someembodiments, the acid may include an organic acid, an inorganic acid, orthe like, or any combination thereof. Exemplary organic acid may includecarboxylic acid (e.g., formic acid, acetic acid, oxalic acid, etc.),sulfonic acid (e.g., ethanesulfonic acid, benzenesulfonic acid, etc.),sulfinic acid, or the like, or any combination thereof. Exemplaryinorganic acid may include hydrochloric acid, sulfuric acid, nitricacid, phosphoric acid, or the like, or any combination thereof. In someembodiments, a concentration of the acid may be 1%˜15%. Preferably, theconcentration of the acid may be 3%˜13%. More preferably, theconcentration of the acid may be 5%˜11%. More preferably, theconcentration of the acid may be 6%˜10%. More preferably, theconcentration of the acid may be 7%˜9%. More preferably, theconcentration of the acid may be 7.5%˜8.5%. A soaking time of the acidmay be 0.1 hours˜10 hours. Preferably, the soaking time of the acid maybe 0.5 hours˜7 hours. More preferably, the soaking time of the acid maybe 0.6 hours˜5 hours. More preferably, the soaking time of the acid maybe 0.8 hours˜4 hours. More preferably, the soaking time of the acid maybe 1 hours˜3 hours. More preferably, the soaking time of the acid may be1.5 hours˜2.5 hours. After the soaking, the crucible may be cleaned withpure water and dried. The impurity cleaning may refer to remove theimpurity in the crucible. The crucible may be wiped with medicalalcohol.

In some embodiments, the second preprocessing operation may include atleast one of an ingredient mixing operation or a pressing operation atroom temperature. It can be understood that uniformly mixed reactantsmay be conducive to the subsequent growth of the crystal. Exemplarymixing device may include but is not limited to a three-dimensionalmotion mixer, a double cone mixer, a vacuum mixer, a coulter mixer, a Vmixer, a conical twin-screw screw mixer, a planetary mixer, a horizontalscrew mixer, etc. A mixing time of the reactants may be 0.5 hours˜48hours. Preferably, the mixing time of the reactants may be 1 hours˜48hours. More preferably, the mixing time of the reactants may be 6hours˜42 hours. More preferably, the mixing time of the reactants may be12 hours˜36 hours. More preferably, the mixing time of the reactants maybe 18 hours˜30 hours. More preferably, the mixing time of the reactantsmay be 21 hours˜27 hours.

The pressing operation may refer to an operation in which a certainpressure may be applied to the reactants to transform the reactants froma dispersed state into a body with an initial shape, for example, acylindrical shape. The pressed reactants may have a volume smaller thanthat of the reactants in the dispersed state, and is easier to be putinto a reaction device (e.g., a reaction crucible) in one time.Meanwhile, the pressing operation may discharge the air contained in thereactants in the dispersed state to reduce an impact of the air on thecrystal growth in subsequent reactions. The pressing operation may beperformed by an isostatic pressing device such as a cold isostaticpressing device. The reactants may be placed in a pressing tank andpressed into the body with the initial shape. The pressure used duringthe pressing operation may be 100 MPa˜300 MPa. Preferably, the pressureused during the pressing operation may be 150 MPa˜250 MPa. Morepreferably, the pressure used during the pressing operation may be 160MPa˜240 MPa. More preferably, the pressure used during the pressingoperation may be 170 MPa˜230 MPa. More preferably, the pressure usedduring the pressing operation may be 180 MPa˜220 MPa. More preferably,the pressure used during the pressing operation may be 190 MPa˜210 MPa.More preferably, the pressure used during the pressing operation may be200 MPa.

In a third step, a flowing gas may be introduced into the crystal growthdevice after the crystal growth device is sealed. In some embodiments,the sealing of the crystal growth device may refer to that except fornecessary contact, there is no gas exchange between the crystal growthdevice and the atmospheric environment. For example, a hearth of an opensingle crystal growth furnace may be opened and an operator (e.g., aworker) may directly observe the temperature field device in the opensingle crystal growth furnace, whereas, the temperature field deviceshould be sealed and have no gas exchange with the atmosphericenvironment. As another example, an interior of a vacuum single crystalgrowth furnace may be vacuum, and the crystal growth device may have nogas exchange with the atmospheric environment. To realize the seal ofthe crystal growth device, a sealing ring, vacuum grease, and/or othersealing material may be mounted at joints among various components ofthe crystal growth device. It can be understood that a suitableprotective gas may reduce volatilization of a reactant (e.g., siliconoxide) to a certain extent, thereby solving a problem of deviation ofcrystal components during the crystal growth. In some embodiments, theflowing gas may be introduced into the crystal growth device (e.g., thetemperature field device) after the crystal growth device is sealed. Theflowing gas may refer to a protective gas that enters from an inlet ofthe crystal growth device and flows out from an outlet of the crystalgrowth device. The flowing gas may include oxygen, inert gas, or thelike, or any combination thereof. It should be noted that the inert gasdescribed in the present disclosure may include nitrogen. In someembodiments, when the flowing gas is a mixed gas of oxygen and one ormore of nitrogen and inert gas, a volume ratio of oxygen may be0.001%˜10% of the mixed gas in an initial stage of the crystal growthprocess, e.g., a stage before cooling the crystal. Preferably, thevolume ratio of oxygen may be 0.01%˜10%. More preferably, the volumeratio of oxygen may be 0.1%˜10%. More preferably, the volume ratio ofoxygen may be 1%˜10%. More preferably, the volume ratio of oxygen may be2%˜9%. More preferably, the volume ratio of oxygen may be 3%˜8%. Morepreferably, the volume ratio of oxygen may be 4%˜7%. More preferably,the volume ratio of oxygen may be 5%˜6%. To ensure that the flowing gasmay not affect the reactants, for example, to bring in an impurity,purity of the flowing gas may be greater than 99%. Preferably, thepurity of the flowing gas may be greater than 99.9%. More preferably,the purity of the flowing gas may be greater than 99.99%. Morepreferably, the purity of the flowing gas may be greater than 99.999%.When introducing the flowing gas to the crystal growth device, a flowrate of the flowing gas may be 0.01 L/min˜50 L/min. Preferably, the flowrate of the flowing gas may be 0.1 L/min˜50 L/min. More preferably, theflow rate of the flowing gas may be 1 L/min˜50 L/min. More preferably,the flow rate of the flowing gas may be 5 L/min˜45 L/min. Morepreferably, the flow rate of the flowing gas may be 10 L/min˜40 L/min.More preferably, the flow rate of the flowing gas may be 15 L/min˜35L/min. More preferably, the flow rate of the flowing gas may be 20L/min˜30 L/min. More preferably, the flow rate of the flowing gas may be21 L/min˜29 L/min. More preferably, the flow rate of the flowing gas maybe 22 L/min˜28 L/min. More preferably, the flow rate of the flowing gasmay be 23 L/min˜27 L/min. More preferably, the flow rate of flowing gasmay be 24 L/min˜26 L/min.

In a fourth step, the crystal growth device may be activated and thecrystal growth may be executed based on the Czochralski technique. Insome embodiments, the activating of the crystal growth device mayinclude energizing and/or introducing a cooling liquid (e.g., water).The reactants may be used for the crystal growth after being melted byheating. After being energized, a medium frequency induction coilmounted in the single crystal growth furnace may heat the crucible tomelt the reactants in the crucible. In some embodiments, a melting timeof the reactants may be 5 hours˜48 hours by heating the reactants duringa crystal growth process. Preferably, the melting time of the reactantsmay be 10 hours˜40 hours. More preferably, the melting time of thereactants may be 15 hours˜35 hours. More preferably, the melting time ofthe reactants may be 20 hours˜30 hours. More preferably, the meltingtime of the reactants may be 22 hours˜28 hours. More preferably, themelting time of the reactants may be 23 hours˜27 hours. More preferably,the melting time of the reactants may be 24 hours˜26 hours. Morepreferably, the melting time of the reactants may be 24.5 hours˜25.5hours. It should be understood that a high temperature (e.g., 1900° C.)is required during the crystal growth, a plenty of heat radiation may begenerated to the external environment. Further, since the crystal growthtime (e.g., four days to forty days) is relatively long, the heatradiation may affect the performance of the crystal growth device.Accordingly, a circulation cooling fluid may be used to reduce the heatradiation. The circulation cooling liquid may include water, ethanol,ethylene glycol, isopropanol, n-hexane, or the like, or any combinationthereof. For example, the circulation cooling liquid may include a 50:50mixture of water and ethanol.

The Czochralski technique disclosed in the present disclosure mayinclude a melting process, a seed crystal preheating process, a seedingprocess, a temperature adjustment process, a necking process, ashouldering process, an constant diameter growth process, an endingprocess, a cooling process, a crystal removing process, etc. The meltingprocess may refer to a process in which the temperature may be increasedto a certain value via a temperature increasing process, the reactantsmay be melted to form a melt, and a certain temperature (i.e.,temperature gradient) can be kept in the crystal growth device. Thecrucible in the crystal growth device may be used as a heater, and heatmay be radiated from the crucible to the surroundings to form thetemperature gradient in the crystal growth device. The temperaturegradient may refer to a change rate of the temperature at a certainpoint toward a temperature of an adjacent point in the crystal growthdevice, which may also be referred to as a change rate of thetemperature per unit distance. Merely by way of example, a temperaturechange from a point M to a point N is (T1−T2), and a distance betweenthe two points is (r1−r2), and the temperature gradient from the point Mto the point N is ΔT=(T1−T2)/(r1−r2). During the crystal growth, asuitable temperature gradient is needed. For example, during the crystalgrowth, a large enough temperature gradient ΔT along a verticaldirection is need, which can disperse the latent heat of crystallizationgenerated during the crystal growth, thereby keep the crystal growthstable. Meanwhile, a temperature of the melt below a growth interfaceshould be higher than a crystallization temperature, so that the localgrowth of crystal would not be too fast and the growth interface wouldbe stable, thereby keeping the growth stable. The temperature gradientmay be determined based on a location of a heating center. In someembodiments, during the melting process, the reactants may be melted andthen solidified to form a polycrystalline material, when a diameter ofthe polycrystalline material reaches 40 mm, the temperature increasingoperation may be stopped. An upper limit of the temperature increasingoperation may be determined according to a temperature or a heatingpower (e.g., a power of the induction coil) at a time when a screw rodstarted to be pulled up when the crystal growth device was used at thelast time. For example, the heating power may be less than the heatingpower at the time when the pulling rod started to be pulled up at thelast time by 300-500 watts. A temperature increasing rate may bedetermined based on the temperature at which the pulling started to bepulled up at the last time. For example, the temperature increasing ratemay be a ratio the temperature and the time (e.g., 24 hours). Aftertemperature increasing operation is completed, the temperature may bemaintained for 0.5 hours-1 hour. According to a melting condition of thereactants, the temperature may be continually increased or decreased.

In some embodiments, during the crystal growth, a melting time of a heattreatment for melting the reactants may be 5˜48 hours. Preferably, themelting time of the reactants may be 7 hours˜46 hours. More preferably,the melting time may be 9 hours˜44 hours. More preferably, the meltingtime may be 11 hours˜42 hours. More preferably, the melting time may be13 hours˜40 hours. More preferably, the melting time may be 15 hours˜38hours. More preferably, the melting time may be 17 hours˜36 hours. Morepreferably, the melting time may be 19 hours˜34 hours. More preferably,the melting time may be 21 hours˜32 hours. More preferably, the meltingtime may be 23 hours˜30 hours. More preferably, the melting time may be25 hours˜28 hours. More preferably, the melting time may be 10 hours˜30hours.

The seed crystal preheating process may refer to a process in which theseed crystal may be fixed on a top of the pulling rod and slowly droppedinto the temperature field during the melting process, which can make atemperature of the seed crystal close to that of the melt, therebyavoiding cracking of the seed crystal when a supercooled seed crystalcontacts with the melt in subsequent operations. During the seed crystalpreheating process, a dropping speed of the seed crystal may be 50mm/h˜800 mm/h. More preferably, the dropping speed of the seed crystalmay be 100 mm/h˜750 mm/h. More preferably, the dropping speed of theseed crystal may be 150 mm/h˜700 mm/h. More preferably, the droppingspeed of the seed crystal may be 200 mm/h˜650 mm/h. More preferably, thedropping speed of the seed crystal may be 250 mm/h˜600 mm/h. Morepreferably, the dropping speed of the seed crystal may be 300 mm/h˜550mm/h. More preferably, the dropping speed of the seed crystal may be 350mm/h˜500 mm/h. More preferably, the dropping speed of the seed crystalmay be 400 mm/h˜450 mm/h. During preheating the seed crystal process, adistance between the seed crystal and an upper surface of the reactantsmay be 5 mm˜10 mm. Preferably, the distance between the seed crystal andthe upper surface of the reactants may be 6 mm˜9 mm. Preferably, thedistance between the seed crystal and the upper surface of the reactantsmay be 7 mm˜8 mm.

The seeding process may refer to a process in which the pulling rod maybe dropped to cause the seed crystal to contact with the melt after adiameter of the reactants is melt to be less than a preset diameter orthe reactants are melted to form a melt. A dropping speed of the seedcrystal may be 5 mm/h˜100 mm/h. Preferably, the dropping speed of theseed crystal may be 10 mm/h˜90 mm/h. More preferably, the dropping speedof the seed crystal may be 20 mm/h˜80 mm/h. More preferably, thedropping speed of the seed crystal may be 30 mm/h˜70 mm/h. Morepreferably, the dropping speed of the seed crystal may be 40 mm/h˜60mm/h. More preferably, the dropping speed of the seed crystal may be 50mm/h˜60 mm/h. The temperature adjustment process may refer to a processin which a temperature in the crystal growth device may be adjusted to asuitable temperature for the crystal growth. In some embodiments,whether the temperature is suitable may be determined based on a changeat a solid-liquid interface of the seed crystal. A power may bedecreased in response to a determination that the temperature is higherthan a temperature threshold, and the power may be increased in responseto a determination that the temperature is lower than the temperaturethreshold until that the seed crystal slightly shrinks. After thetemperature is adjusted as a suitable temperature, the seed crystal maybe sunk by 0.1 mm˜50 mm. Preferably, the seed crystal may be sunk by 1mm 50 mm. More preferably, the seed crystal may be sunk by 10 mm˜40 mm.More preferably, the seed crystal may be sunk gain by 20 mm˜30 mm. Morepreferably, the seed crystal may be sunk by 21 mm˜29 mm. Morepreferably, the seed crystal may be sunk by 22 mm˜28 mm. Morepreferably, the seed crystal may be sunk by 23 mm˜27 mm. Morepreferably, the seed crystal may be sunk by 24 mm˜26 mm. In someembodiments, a rate of temperature adjustment may be 100-300 watts/0.1hour. After the temperature adjustment process, the temperature insidethe crystal growth device may be maintained at 1950° C.˜2150° C. for 0.1h˜1 h. Then, the screw rod may be rotated to pull the pulling rod up.After the seed crystal passed through a second cover plate and duringthe subsequent crystal growth process, a rotation rate of the pullingrod may be 0.01 rpm/min˜35 rpm/min. More preferably, the rotation rateof the pulling rod may be 0.1 rpm/min˜35 rpm/min. More preferably, therotation rate of the pulling rod may be 1 rpm/min˜35 rpm/min. Morepreferably, the rotation rate of the pulling rod may be 5 rpm/min˜30rpm/min. More preferably, the rotation rate of the pulling rod may be 10rpm/min˜25 rpm/min. More preferably, the rotation rate of the pullingrod may be 15 rpm/min˜20 rpm/min.

The necking process may refer to a process in which the temperature maybe slowly increased to cause a temperature of a zero point of the melt(i.e., a temperature of a center point of the liquid surface incrucible) to be slightly higher than the melting point of the crystal, adiameter of a newly grown crystal during the rotation and pulling up ofthe seed crystal may be gradually decreased. The necking process mayreduce the extension of crystal dislocations from the seed crystal to asingle crystal below a neck. The shouldering processing may refer to aprocess in which when atoms or molecules on a solid-liquid interface ata boundary between the seed crystal and the melt begin to be arranged ina structure of the seed crystal, the temperature in the temperaturefield may be slowly decreased according to a real-time growth rate ofthe crystal to expand the seed crystal according to a preset angle. Insome embodiments, the shoulder angle may be 30 degrees˜70 degrees. Morepreferably, the shoulder angle may be 40 degrees˜60 degrees. Morepreferably, the shoulder angle may be 45 degrees˜55 degrees. Morepreferably, the shoulder angle may be 46 degrees˜54 degrees. Morepreferably, the shoulder angle may be 47 degrees˜53 degrees. Morepreferably, the shoulder angle may be 48 degrees˜52 degrees. Morepreferably, the shoulder angle may be 49 degrees˜51 degrees. A shoulderlength may be 40 mm˜130 mm. Preferably, the shoulder length may be 50mm˜120 mm. More preferably, the shoulder length may be 60 mm˜110 mm.More preferably, the shoulder length may be 70 mm˜100 mm. Morepreferably, the shoulder length may be 80 mm˜90 mm.

The constant diameter growth process may refer to a process in which arod-like structure with a diameter determined during the shoulderingprocess may be obtained. In some embodiments, the diameter of thecrystal growth may be 10 mm˜200 mm. Preferably, the length of theconstant diameter of the crystal growth may be 20 mm˜180 mm. Morepreferably, the length of the constant diameter of the crystal growthmay be 50 mm˜150 mm. More preferably, the length of the constantdiameter of the crystal growth may be 60 mm˜140 mm. More preferably, thelength of the constant diameter of the crystal growth may be 70 mm˜130mm. More preferably, the length of the constant diameter of the crystalgrowth may be 80 mm˜120 mm. More preferably, the length of the constantdiameter of the crystal growth may be 90 mm˜110 mm.

The ending process may refer to a process in which the crystal may beraised up to be separated from the melt when the crystal grows to apredetermined length. The ending process may be a reverse operation ofthe shouldering process. The diameter of the crystal may be reduceduntil the crystal is separated from the melt by changing a pulling speedof the pulling rod, or the diameter of the crystal may be reduced to apreset diameter such as 10 mm. An automatic control program may be usedto calculate a change of the diameter of the crystal based on apredetermined parameter of the ending process, and perform the endingprocess according to a preset angle by increasing or decreasing thetemperature. In some embodiments, an ending angle may be 30 degrees˜70degrees. Preferably, the ending angle may be 40 degrees˜60 degrees. Morepreferably, the ending angle may be 45 degrees˜55 degrees. Morepreferably, the ending angle may be 46 degrees˜54 degrees. Morepreferably, the ending angle may be 47 degrees˜53 degrees. Morepreferably, the ending angle may be 48 degrees˜52 degrees. Morepreferably, the ending angle may be 49 degrees˜51 degrees. An endinglength of the crystal may be 40 mm˜110 mm. More preferably, the endinglength of the crystal may be 50 mm˜100 mm. More preferably, the endinglength of the crystal may be 60 mm˜90 mm. More preferably, the endinglength of the crystal may be 70 mm˜80 mm.

The cooling process may refer to a process in which a temperature may beslowly decreased after the ending process is completed, to eliminate astress within the crystal, which may be formed in the high-temperaturecrystal growth. The cooling process may prevent cracking of the crystalcaused by a sudden drop of the temperature. According to a crystalgrowth method of the present disclosure, an annealing operation may beperformed on the crystal during the cooling process. By introducing anoxygen-rich flowing gas into the crystal growth device, on one hand, avolatilization of SiO₂ may be reduced and a poor performance consistencyof the crystal caused by the composition deviation during the crystalgrowth may be avoided; on the other hand, an oxygen-deficient conditionwould not occur during the crystal growth, thereby reducing crystallattice distortion caused by occurrence of oxygen vacancies in thecrystal. In this case, the annealing operation can be performed duringthe crystal growth, accordingly, it is not necessary to perform theannealing operation after the crystal growth. During the coolingprocess, when the temperature drops to 1400° C.˜800° C., the volumeratio of oxygen in the flowing gas may be increased to cause the oxygento effectively diffuse into the crystal. In some embodiments, duringincreasing the volume ratio of oxygen, a cooling rate of the crystal mayalso be slowed, or a stepwise cooling process may be performed to causethe oxygen to diffuse more fully. In some embodiments, when thetemperature drops to 1400° C.˜800° C., the volume of oxygen in theflowing gas may be increased to 1%˜30% during the cooling process. Morepreferably, when the temperature drops to 1400° C.˜800° C., the volumeratio of oxygen in the flowing gas may be increased to 2%˜28%. Morepreferably, when the temperature drops to 1400° C.˜800° C., the volumeratio of oxygen in the flowing gas may be increased to 5%˜25%. Morepreferably, when the temperature drops to 1400° C.˜800° C., the volumeratio of oxygen in the flowing gas may be increased to 10%˜20%. Morepreferably, when the temperature drops to 1400° C.˜800° C., the volumeratio of oxygen in the flowing gas may be increased to 13%˜17%. Morepreferably, when the temperature drops to be 1400° C.˜800° C., thevolume ratio of oxygen in the flowing gas may be increased to 14%˜16%.When the temperature is lower than 800° C., the volume ratio of oxygenin the flowing gas may be at least decreased to a volume ratio of oxygenin a previous crystal growth process, which may be 0.001%˜20% and othermentioned temperature. In some embodiments, a cooling time of thecrystal may be 20 hours˜100 hours. More preferably, the cooling time ofcrystal may be 30 hours˜90 hours. More preferably, the cooling time ofthe crystal may be 40 hours˜80 hours. More preferably, the cooling timeof the crystal may be 50 hours˜70 hours. More preferably, the coolingtime of the crystal may be 55 hours 65 hours. In some embodiments,assuming that T is the temperature after the ending process, adecreasing rate of a crystal temperature during the cooling process maybe T/(20−100) hours. In some embodiments, a decreasing rate of thecrystal temperature may be 15° C./h˜95° C./h. More preferably, thedecreasing rate of the crystal temperature may be 20° C./h˜65° C./h.More preferably, the decreasing rate of the crystal temperature may be23° C./h˜47° C./h. More preferably, the decreasing rate of the crystaltemperature may be 26° C./h˜38° C./h. More preferably, the decreasingrate of the crystal temperature may be 28° C./h˜34° C./h. When an outputheating power (e.g., the heating power of the induction coil) is 0, thecrystal growth may end.

The crystal removing process may refer to a process in which the growncrystal may be taken out from the crystal growth device when an internaltemperature of the crystal growth device drops to the room temperature.In the crystal growth process, according to a setting of various processparameters in different stages of the crystal growth process, the growthrate of the crystal may be 0.01 mm/h˜6 mm/h. Preferably, the growth rateof the crystal may be 0.1 mm/h˜6 mm/h. More preferably, the growth rateof the crystal may be 1 mm/h˜6 mm/h. More preferably, the growth rate ofthe crystal may be 2 mm/h˜5 mm/h. More preferably, the growth rate ofthe crystal may be 3 mm/h˜4 mm/h. A diameter of an obtained crystal maybe 50 mm˜115 mm. A diameter of a grown crystal may be equal to orgreater than 60 mm, such as 60 mm˜100 mm (e.g., 60 mm), 70 mm˜100 mm(e.g., 95 mm). A constant diameter may be reached to more than 180 mm,such as 180 mm-200 mm, 200 mm-190 mm, or 195 mm-200 mm.

In some embodiments, one or more processes in the crystal growth may becontrolled by a PID controller. The one or more process may include butare not limited to the necking process, the shouldering process, theconstant diameter growth process, the ending process, the coolingprocess, etc. In some embodiments, the PID parameter may be 0.1˜5.Preferably, the PID parameter may be 0.5˜4.5. More preferably, the PIDparameter may be 1˜4. More preferably, the PID parameter may be 1.5˜3.5.More preferably, the PID parameter may be 2˜3. More preferably, the PIDparameter may be 2.5˜3.5.

It should be noted that the embodiments mentioned above are only used toillustrate the technical solutions of the present disclosure but not tolimit the technical solutions. Various modifications to the disclosedembodiments will be readily apparent to those skilled in the art, andthe general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the present disclosure. Thus, the present disclosure is not limitedto the embodiments shown, but to be accorded the widest scope consistentwith the claims.

FIG. 1 is a flowchart illustrating an exemplary method for growing acrystal according to some embodiments of the present disclosure. In someembodiments, the method shown in process 100 may be implemented based onthe Czochralski technique.

In step 110, reactants may be weighted based on a molar ratio of thereactants according to a reaction equation for generating the oxidecrystal after a first preprocessing operation is performed on thereactants. Taking a growth of Ce:LSO and Ce:LYSO as an example, thereaction equation may be denoted by Equations below:(1−x−y)Lu₂O₃+SiO₂+2xCeO₂ +yCe₂O₃→Lu_(2(1-x-y))Ce_(2(x+y))SiO₅+x/2O₂↑  (1)(1−x−y−z)Lu₂O₃ +zY₂O₃+SiO₂+2xCeO₂+yCe₂O₃→Lu_(2(1-x-y-z))Y_(2z)Ce_(2(x+y))SiO₅ +x/2O₂↑  (2)

It can be understood that structures of grown Ce:LSO and Ce:LYSO mayinclude Ce_(x):Lu_(2(1-x))SiO₅ or Ce_(x):Lu_(2(1-x-y))Y_(2y)SiO₅. In theabove equations, x represents a doping concentration of trivalent ceriumion (Ce³⁺), that is, a proportion of Ce³⁺ occupying atomic lattice ofLutetium, y represents a doping concentration of tetravalent cerium ion(Ce⁴⁺), that is, a proportion of Ce⁴⁺ occupying atomic lattice ofLutetium, and z represents a concentration of yttrium (Y) ion in crystallattice of the Ce:LSO. In some embodiments, a value of x may be0.000001˜0.06. Preferably, the value of x may be 0.00001˜0.06. Morepreferably, the value of x may be 0.0001˜0.06. More preferably, thevalue of x may be 0.001˜0.06. More preferably, the value of x may be0.01˜0.06. More preferably, the value of x may be 0.02˜0.05. Morepreferably, the value of x may be 0.03˜0.04. More preferably, the valueof x may be 0.031˜0.039. More preferably, the value of x may be0.032˜0.038. More preferably, the value of x may be 0.033˜0.037. Morepreferably, the value of x may be 0.036˜0.036. It can be understood thata luminescence center of the crystal is Ce³⁺, then a low dopingconcentration of Ce³⁺ may cause a low concentration of activated ions,less luminescence center of the crystal, and a low luminescenceintensity, whereas, a high doping concentration of Ce³⁺ may cause aconcentration quenching, thereby reducing luminescence efficiency of thecrystal. According to the method of the present disclosure, the dopingconcentration of Ce³⁺ may be reasonably controlled to improve theluminescence efficiency of the crystal. In some embodiments, the dopingconcentration of Ce³⁺ (a value of y) may be 0˜0.006. The value of y maybe 0.001˜0.006. The value of y may be 0.002˜0.005. The value of y may be0.003˜0.004. The value of y may be 0.0031˜0.0039. The value of y may be0.0032˜0.0038. The value of y may be 0.0033˜0.0037. The value of y maybe 0.0034˜0.0036. In some embodiments, a value of z may be 0˜1. Thevalue of z may be 0.1˜0.9. The value of z may be 0.1˜0.9. The value of zmay be 0.2˜0.8. The value of z may be 0.3˜0.7. The value of z may be0.4˜0.6. The value of z may be 0.42˜0.58. The value of z may be0.44˜0.56. The value of z may be 0.46˜0.54. The value of z may be0.48˜0.52. The value of z may be 0.49˜0.51.

It can be understood that during the growth of the crystal, silicondioxide (SiO2) may volatilize under a heating condition, which may causecomposition deviation of the generated crystal, composition differenceamong crystals generated in different times, and a poor growthrepeatability. According to some embodiments of the present disclosure,an excessive amount of silicon dioxide may be used to avoid compositiondeviation and poor growth repeatability caused by the volatilization ofthe silicon dioxide to a certain extent. In some embodiments, a weightof the silicon dioxide may excess of 0.01%˜10% of its weight or thetotal weight of the reactants as determined according to the reactionequation. Preferably, the weight of the silicon dioxide may excess of0.1%˜10% of its weight or the total weight of the reactants. Morepreferably, the weight of the silicon dioxide may excess of 0.12%˜9% ofits weight or the total weight of the reactants. More preferably, theweight of the silicon dioxide may excess of 0.13%˜8% of its weight orthe total weight of the reactants. More preferably, the weight of thesilicon dioxide may excess of 0.14%˜7% of its weight or the total weightof the reactants. More preferably, the weight of the silicon dioxide mayexcess of 0.15%˜6% of its weight or the total weight of the reactants.More preferably, the weight of the silicon dioxide may excess of0.16%˜5% of its weight or the total weight of the reactants. Morepreferably, the weight of the silicon dioxide may excess of 0.17%˜4% ofits weight or the total weight of the reactants. More preferably, theweight of the silicon dioxide may excess of 0.18%˜3% of its weight orthe total weight of the reactants. More preferably, the weight of thesilicon dioxide may excess of 0.2%˜2% of its weight or the total weightof the reactants. In some embodiments, when x=0.15% and y=0.3%, theweight of the silicon dioxide may excess of 0.2% of its own weight orthe total weight of the reactants, or when x=0.16%, y=0.3%, and z=20%,the weight of the silicon dioxide may excess of 2% of its own weight orthe total weight of the reactants.

Purity of the reactants may have a great influence on the scintillationperformance of the crystal. In order to generate the crystal meetingrequirements, the purity of the reactants for growing the crystal may begreater than 99%. Preferably, the purity of the reactants may be greaterthan 99.9%. More preferably, the purity of the reactants may be greaterthan 99.99%. More preferably, the purity of the reactants may be greaterthan 99.999%.

In some embodiments, the first preprocessing operation may include ahigh temperature roasting operation. It can be understood that the hightemperature roasting operation may be performed on all or a portion ofthe reactants to remove substances such as water and/or organicsubstance(s) of metal element(s) (e.g., Cerium, lutetium, yttrium, etc.)to improve the purity of the reactants. For example, a roastingoperation may be performed to remove water and/or the organicsubstance(s). The roasting operation may be performed using acommercially available high-temperature roasting device such as a mufflefurnace. In some embodiments, a roasting temperature of the reactantsmay be 800° C.˜1400° C. Preferably, the roasting temperature of thereactants may be 900° C.˜1300° C. More preferably, roasting temperatureof the reactants may be 1000° C.˜1200° C. More preferably, roastingtemperature of the reactants may be 1050° C.˜1150° C. More preferably,roasting temperature of the reactants may be 1060° C.˜1140° C. Morepreferably, roasting temperature of the reactants may be 1070° C.˜1130°C. More preferably, roasting temperature of the reactants may be 1080°C.˜1120° C. More preferably, roasting temperature of the reactants maybe 1090° C.˜1110° C. According to characteristics of the differentreactants, the time of the high-temperature roasting may be not lessthan 5 hours.

In step 120, the reactants on which a second preprocessing operation hasbeen performed may be placed into a crystal growth device after anassembly preprocessing operation is performed on at least one componentof the crystal growth device. In some embodiments, the at least onecomponent of the crystal growth device may include a crucible. In someembodiments, the crucible may be made of a high melting point materialthat can be heated by electromagnetic induction, for example, iridium(Ir), molybdenum (Mo), tungsten (W), rhenium (Re), graphite (C),tungsten-molybdenum alloy, or the like, or any combination thereof. Insome embodiments, the assembly processing operation may include at leastone of a coating operation, an acid soaking and cleaning operation, oran impurity cleaning operation on the crucible. It can be understoodthat the assembly processing operation may prevent the crystal frombeing contaminated by an impurity and improve a purity of the crystal.The coating operation may refer to that the crucible may be coated afterbeing cleaned. The crucible may volatize and/or deform in a hightemperature condition. Volatiles may float on a surface of the melt orinside the crystal, which may result in that the seeding of the crystalgrowth becomes difficult or wrapping materials are introduced into thecrystal, and further result in a failure of the crystal growth and thatthe quality of the crystal may be affected. In addition, a lower middlepart of the crucible may deform due to a hydraulic pressure caused by amelt with high-density melting point under the high temperaturecondition, which may affect the temperature gradient of the crystalgrowth, and in severe case, may cause a crack and leakage of thecrucible, and further result in a failure of the crystal growth and thatthe quality of the crystal may be affected. Therefore, it is necessaryto coat the crucible to reduce the volatilization and deformation of thecrucible. The coating may include a high temperature resistant material,such as Y2O3, ZrO2, etc. The acid cleaning operation may refer tosoaking an inner wall of the crucible with an acid with a certainconcentration (e.g., 1%-15%) for a period (e.g., 2 hours) after thecoating operation. In some embodiments, the acid may include an organicacid, an inorganic acid, or the like, or any combination thereof.Exemplary organic acid may include carboxylic acid (e.g., formic acid,acetic acid, oxalic acid, etc.), sulfonic acid (e.g., ethanesulfonicacid, benzenesulfonic acid, etc.), sulfinic acid, or the like, or anycombination thereof. Exemplary inorganic acid may include hydrochloricacid, sulfuric acid, nitric acid, phosphoric acid, or the like, or anycombination thereof. In some embodiments, a concentration of the acidmay be 1% 15%. Preferably, the concentration of the acid may be 3%˜13%.More preferably, the concentration of the acid may be 5%˜11%. Morepreferably, the concentration of the acid may be 6%˜10%. Morepreferably, the concentration of the acid may be 7% 9%. More preferably,the concentration of the acid may be 7.5%˜8.5%. A soaking time of theacid may be 0.1 hours˜10 hours. Preferably, the soaking time of the acidmay be 0.5 hours˜7 hours. More preferably, the soaking time of the acidmay be 0.6 hours˜5 hours. More preferably, the soaking time of the acidmay be 0.8 hours˜4 hours. More preferably, the soaking time of the acidmay be 1 hours˜3 hours. More preferably, the soaking time of the acidmay be 1.5 hours˜2.5 hours. After the soaking, the crucible may becleaned with pure water and dried. The impurity cleaning may refer to aprocess for removing the impurity in the crucible. The crucible may bewiped with medical alcohol. After the processing operation, the cruciblemay be mounted.

In some embodiments, the second preprocessing operation may include atleast one of an ingredient mixing operation and/or a pressing operationat room temperature. It can be understood that uniformly mixed reactantsmay be conducive to the subsequent growth of the crystal. Exemplarymixing device may include but is not limited to a three-dimensionalmotion mixer, a double cone mixer, a vacuum mixer, a coulter mixer, a Vmixer, a conical twin-screw screw mixer, a planetary mixer, a horizontalscrew mixer, etc. A mixing time of the reactants may be 0.5 hours˜48hours. Preferably, the mixing time may be 1 hour 48 hours. Morepreferably, the mixing time may be 6 hours˜42 hours. More preferably,the mixing time may be 12 hours˜36 hours. More preferably, the mixingtime may be 18 hours˜30 hours. More preferably, the mixing time may be21 hours˜27 hours.

The pressing operation may refer to an operation in which a certainpressure may be applied to the reactants to transform the reactants froma dispersed state into a body with an initial shape, for example, acylindrical shape. The pressed reactants may have a volume smaller thanthat of the reactants in the dispersed state, and is easier to be putinto a reaction device (e.g., a reaction crucible) in one time.Meanwhile, the pressing operation may discharge the air contained in thereactants in the dispersed state to reduce an impact of the air on thecrystal growth in subsequent reactions. The pressing operation may beperformed by an isostatic pressing device such as a cold isostaticpressing device. The reactants may be placed in a pressing tank andpressed into the body with the initial shape. The pressure used duringthe pressing operation may be 100 MPa˜300 MPa. Preferably, the pressureused during the pressing operation may be 150 MPa˜250 MPa. Morepreferably, the pressure used during the pressing operation may be 160MPa˜240 MPa. More preferably, the pressure used during the pressingoperation may be 170 MPa˜230 MPa. More preferably, the pressure usedduring the pressing operation may be 180 MPa˜220 MPa. More preferably,the pressure used during the pressing operation may be 190 MPa˜210 MPa.More preferably, the pressure used during the pressing operation may be200 MPa.

In some embodiments, the crystal growth device may include a singlecrystal growth furnace and a temperature field device. A type of thesingle crystal growth furnace may include an open type or a vacuum type,which is not limited in the present disclosure. The temperature fielddevice may be used in the single crystal growth furnace to provide atemperature gradient for the crystal growth, and ensure the stability ofa crystallization process of the crystal. A temperature field with goodsymmetry and stability may avoid problems of cracking and abnormalgrowth during the crystal growth. The temperature field device mayinclude a first hollow column and two cover plates covering two ends ofthe first hollow column, respectively. Specifically, two cover platesmay be connected to the two ends of the first hollow column. Theconnection may include a bonding connection, a welding connection, ariveting connection, a key connection, a bolting connection, a buckleconnection, or the like, or any combination thereof. Alternatively, afirst end of the two ends of the first hollow column may be connected toone cover plate of the two cover plates (e.g., via a detachableconnection), a second end of the two ends may be integrally formed withthe other cover plate, or connected to the other cover plate via anon-detachable connection. A second hollow column with a height lessthan that of the first hollow column may be mounted inside the firsthollow column. A space between the first hollow column and the secondhollow column and/or a space in the second hollow column may be filledwith a substance used for heat preservation. For example, the spacebetween the first hollow column and the second hollow column and thespace in the second hollow column may be filled with the substance. Asanother example, the space between the first hollow column and thesecond hollow column may be filled with a substance used for heatpreservation, and the space in the second hollow column may not befilled with the substance. As a further example, the space between thefirst hollow column and the second hollow column may not be filled withthe substance, and the space in the second hollow column may be filledwith the substance. The substance filled in the second hollow column mayalso be configured to support a crucible used for holding the reactants.A heater may be mounted above the crucible, which may be configured todecrease the temperature gradient above the crucible. In addition, anend of the second hollow column near the cover plate mounted on a top ofthe first hollow column may be connected with a heat preservation boardto further improve the heat preservation effect. In this case, thetemperature field device described in the present disclosure may providea reaction environment with good heat preservation performance, stabletemperature field gradient, and good symmetry due to the hollow columnsand the substance used for heat preservation, which may be beneficial tothe crystal growth. More descriptions regarding the temperature fielddevice may be found elsewhere in the present disclosure (e.g., FIGS.2-5), which are not repeated here.

In step 130, a flowing gas may be introduced into the crystal growthdevice after the crystal growth device is sealed. In some embodiments,the sealing of the crystal growth device may refer to that except fornecessary contact, there is no gas exchange between the crystal growthdevice and the atmospheric environment. For example, a hearth of an opensingle crystal growth furnace may be opened and an operator (e.g., aworker) may directly observe the temperature field device in the opensingle crystal growth furnace, whereas, the temperature field deviceshould be sealed and have no gas exchange with the atmosphericenvironment. As another example, an interior of a vacuum single crystalgrowth furnace may be vacuum, and the crystal growth device may have nogas exchange with the atmospheric environment. To realize the seal ofthe crystal growth device, a sealing ring, vacuum grease, and/or othersealing material may be mounted at joints among various components ofthe crystal growth device. It can be understood that a suitableprotective gas may reduce volatilization of a reactant (e.g., siliconoxide) to a certain extent, thereby solving a problem of compositiondeviation of the crystal during the crystal growth. In some embodiments,the flowing gas may be introduced into the crystal growth device (e.g.,the temperature field device) after the crystal growth device is sealed.The flowing gas may enter from an inlet of the crystal growth device andflows out from an outlet of the crystal growth device. The flowing gasmay include oxygen, inert gas, or the like, or any combination thereof.It should be noted that the inert gas described in the presentdisclosure may include nitrogen. In some embodiments, when the flowinggas is a mixed gas of oxygen and one or more of nitrogen and inert gas,a volume ratio of oxygen may be 0.001%˜10%. Preferably, the volume ratioof oxygen may be 0.01%˜10%. More preferably, the volume ratio of oxygenmay be 0.1%˜10%. More preferably, the volume ratio of oxygen may be1%˜10%. More preferably, the volume ratio of oxygen may be 2% 9%. Morepreferably, the volume ratio of oxygen may be 3%˜8%. More preferably,the volume ratio of oxygen may be 4%˜7%. More preferably, the volumeratio of oxygen may be 5%˜6%. To ensure that the flowing gas may notaffect the reactants, for example, to bring in an impurity, purity ofthe flowing gas may be greater than 99%. Preferably, the purity of theflowing gas may be greater than 99.9%. More preferably, the purity ofthe flowing gas may be greater than 99.99%. More preferably, the purityof the flowing gas may be greater than 99.999%. When introducing theflowing gas to the crystal growth device, a flow rate of the flowing gasmay be 0.01 L/min˜50 L/min. Preferably, the flow rate of the flowing gasmay be 0.1 L/min˜50 L/min. More preferably, the flow rate of the flowinggas may be 1 L/min˜50 L/min. More preferably, the flow rate of theflowing gas may be 5 L/min˜45 L/min. More preferably, the flow rate ofthe flowing gas may be 10 L/min˜40 L/min. More preferably, the flow rateof the flowing gas may be 15 L/min˜35 L/min. More preferably, the flowrate of the flowing gas may be 20 L/min˜30 L/min. More preferably, theflow rate of the flowing gas may be 21 L/min˜29 L/min. More preferably,the flow rate of the flowing gas may be 22 L/min˜28 L/min. Morepreferably, the flow rate of the flowing gas may be 23 L/min˜27 L/min.More preferably, the flow rate of flowing gas may be 24 L/min˜26 L/min.

In step 140, the crystal growth device may be activated and the crystalgrowth may be executed based on the Czochralski technique. In someembodiments, the activating of the crystal growth device may includeenergizing and/or activating a cooling component. The reactants may beused for the crystal growth after being melted by heating. After beingenergized, a medium frequency induction coil mounted in the singlecrystal growth furnace may heat the crucible to melt the reactants inthe crucible. In some embodiments, a melting time of the reactants maybe 5 hours˜48 hours. Preferably, the melting time of the reactants maybe 10 hours˜40 hours. More preferably, the melting time of the reactantsmay be 15 hours˜35 hours. More preferably, the melting time of thereactants may be 20 hours˜30 hours. More preferably, the melting time ofthe reactants may be 22 hours˜28 hours. More preferably, the meltingtime of the reactants may be 23 hours˜27 hours. More preferably, themelting time of the reactants may be 24 hours˜26 hours. More preferably,the melting time of the reactants may be 24.5 hours˜25.5 hours. Since ahigh temperature (e.g., 1900° C.) is required during the crystal growth,a plenty of heat radiation may be generated to the external environment.Further, since the crystal growth time (e.g., four days to forty days)is relatively long, the heat radiation may affect the performance of thecrystal growth device. Accordingly, the cooling component may be used toreduce the heat radiation. A cooling manner of the cooling component mayinclude a liquid cooling mode, an air cooling mode, or the like, or anycombination thereof. For the liquid cooling mode, a cooling liquid mayinclude water, ethanol, ethylene glycol, isopropanol, n-hexane, or thelike, or any combination thereof. For example, the cooling liquid mayinclude a 50:50 mixture of water and ethanol.

The Czochralski technique disclosed in the present disclosure mayinclude a melting process, a seed crystal preheating process, a seedingprocess, a temperature adjustment process, a necking process, ashouldering process, an constant diameter growth process, an endingprocess, a cooling process, a crystal removing process, etc. The meltingprocess may refer to a process during which the temperature may beincreased to a certain value via a temperature increasing process, thereactants may be melted to form a melt, and a certain temperature (i.e.,temperature gradient) can be kept in the crystal growth device. Thecrucible in the crystal growth device may be used as a heater and heatmay be radiated from the crucible to the surroundings to form thetemperature gradient in the crystal growth device. The temperaturegradient may refer to a change rate of the temperature at a certainpoint toward a temperature of an adjacent point in the crystal growthdevice, which may also be referred to as a change rate of thetemperature per unit distance. Merely by way of example, a temperaturechange from a point M to a point N is (T1−T2), and a distance betweenthe two points is (r1−r2), and the temperature gradient from the point Mto the point N may be represented as ΔT=(T1−T2)/(r1−r2). During thecrystal growth, a suitable temperature gradient is needed. For example,during the crystal growth, a large enough temperature gradient ΔT alonga vertical direction is need, which can disperse the latent heat ofcrystallization generated during the crystal growth, thereby keep thecrystal growth stable. Meanwhile, a temperature of the melt below agrowth interface should be higher than a crystallization temperature, sothat the local growth of crystal would not be too fast and the growthinterface would be stable, thereby keeping the growth stable. Thetemperature gradient may be determined based on a location of a heatingcenter. The heating center during the melting process may affect thedetermination of the temperature gradient. In some embodiments, duringthe melting process, the reactants may be melted and then solidified toform a polycrystalline material, when a diameter of the polycrystallinematerial reaches 40 mm, the temperature increasing operation may bestopped. An upper limit of the temperature increasing operation may bedetermined according to a temperature or a heating power (e.g., a powerof the induction coil) at a time when a screw rod started to be pulledup when the crystal growth device was used at the last time. Forexample, the heating power may be less than the heating power at thetime when the pulling rod started to be pulled up at the last time by300-500 watts. A temperature increasing rate may be determined based onthe temperature at which the pulling started to be pulled up at the lasttime. For example, the temperature increasing rate may be a ratio thetemperature and the time (e.g., 24 hours). After temperature increasingoperation is completed, the temperature may be maintained for 0.5hours˜1 hour. According to a melting condition of the reactants, thetemperature may be continually increased or decreased.

In some embodiments, a melting time of the reactants may be 5 hours˜48hours by heating the reactants during a crystal growth process.Preferably, the melting time of the reactants may be 7 hours˜46 hours.More preferably, the melting time of the reactants may be 9 hours˜44hours. More preferably, the melting time of the reactants may be 11hours˜42 hours. More preferably, the melting time of the reactants maybe 13 hours˜40 hours. More preferably, the melting time of the reactantsmay be 15 hours˜38 hours. More preferably, the melting time of thereactants may be 17 hours˜36 hours. More preferably, the melting time ofthe reactants may be 19 hours˜34 hours. More preferably, the meltingtime of the reactants may be 21 hours˜32 hours. More preferably, themelting time of the reactants may be 23 hours˜30 hours. More preferably,the melting time of the reactants may be 25 hours˜28 hours. Morepreferably, the melting time of the reactants may be 10 hours˜30 hours.

The seed crystal preheating process may refer to a process in which theseed crystal may be fixed on a top of the pulling rod and slowly droppedinto the temperature field during the melting process, which can make atemperature of the seed crystal close to that of the melt, therebyavoiding cracking of the seed crystal when a supercooled seed crystalcontacts with the melt in subsequent operations. During the seed crystalpreheating process, a dropping speed of the seed crystal may be 50mm/h˜800 mm/h. Preferably, the dropping speed of the seed crystal may be100 mm/h˜750 mm/h. More preferably, the dropping speed of the seedcrystal may be 150 mm/h˜700 mm/h. More preferably, the dropping speed ofthe seed crystal may be 200 mm/h˜650 mm/h. More preferably, the droppingspeed of the seed crystal may be 250 mm/h˜600 mm/h. More preferably, thedropping speed of the seed crystal may be 300 mm/h˜550 mm/h. Morepreferably, the dropping speed of the seed crystal may be 350 mm/h˜500mm/h. More preferably, the dropping speed of the seed crystal may be 400mm/h˜450 mm/h. During the seed crystal preheating process, a distancebetween the seed crystal and an upper surface of the reactants may be 5mm˜10 mm. Preferably, the distance between the seed crystal and theupper surface of the reactants may be 6 mm˜9 mm. Preferably, thedistance between the seed crystal and the upper surface of the reactantsmay be 7 mm˜8 mm.

The seeding process may refer to a process in which the pulling rod maybe dropped to cause the seed crystal to contact with the melt after thereactants are completely melted or a diameter of the reactants whichhave not been melted is a predetermined value. A dropping speed of theseed crystal may be 5 mm/h˜100 mm/h. Preferably, the dropping speed ofthe seed crystal may be 10 mm/h˜90 mm/h. More preferably, the droppingspeed of the seed crystal may be 20 mm/h˜80 mm/h. More preferably, thedropping speed of the seed crystal may be 30 mm/h˜70 mm/h. Morepreferably, the dropping speed of the seed crystal may be 40 mm/h˜60mm/h. More preferably, the dropping speed of the seed crystal may be 50mm/h˜60 mm/h. The temperature adjustment process may refer to a processin which a temperature in the crystal growth device may be adjusted to asuitable temperature for the crystal growth. In some embodiments, anoperator may determine whether the temperature is suitable for thecrystal growth by observing a solid-liquid interface of the seedcrystal. A power may be decreased in response to that the temperature ishigher than a temperature threshold, and/or the power may be increasedin response to that the temperature is lower than the temperaturethreshold, until the seed crystal shrinks slightly. During thetemperature adjustment process, the seed crystal may be sunk by 0.1mm˜50 mm. Preferably, the seed crystal may be sunk by 1 mm˜50 mm. Morepreferably, the seed crystal may be sunk by 10 mm˜40 mm. Morepreferably, the seed crystal may be sunk gain by 20 mm˜30 mm. Morepreferably, the seed crystal may be sunk by 21 mm˜29 mm. Morepreferably, the seed crystal may be sunk by 22 mm˜28 mm. Morepreferably, the seed crystal may be sunk by 23 mm˜27 mm. Morepreferably, the seed crystal may be sunk by 24 mm˜26 mm. In someembodiments, a rate of temperature adjustment may be 100-300 watts/0.1hours. After the temperature adjustment process is completed, thetemperature inside the crystal growth device may be kept at 1950°C.˜2150° C. for 0.1 hours˜1 hour. Then, the screw rod may be rotated topull the pulling rod up. After the seed crystal passed through a secondcover plate and during the subsequent crystal growth process, a rotationrate of the pulling rod may be 0.01 rpm/min˜35 rpm/min. More preferably,the rotation rate of the pulling rod may be 0.1 rpm/min˜35 rpm/min. Morepreferably, the rotation rate of the pulling rod may be 1 rpm/min˜35rpm/min. More preferably, the rotation rate of the pulling rod may be 5rpm/min˜30 rpm/min. More preferably, the rotation rate of the pullingrod may be 10 rpm/min˜25 rpm/min. More preferably, the rotation rate ofthe pulling rod may be 15 rpm/min˜20 rpm/min.

The necking process may refer to a process in which the temperature maybe slowly increased to cause a temperature of a zero point of the melt(i.e., a temperature of a center point of the liquid surface incrucible) to be slightly higher than the melting point of the crystal, adiameter of a newly grown crystal during the rotation and pulling up ofthe seed crystal may be gradually decreased. The necking process mayreduce the extension of crystal dislocations from the seed crystal to asingle crystal below a neck. The shouldering processing may refer to aprocess in which when atoms or molecules on a solid-liquid interface ata boundary between the seed crystal and the melt begin to be arranged ina structure of the seed crystal, the temperature in the temperaturefield may be slowly decreased according to a real-time growth rate ofthe crystal to expand the seed crystal according to a preset angle. Insome embodiments, a shoulder angle may be 30 degrees˜70 degrees. Morepreferably, the shoulder angle may be 40 degrees˜60 degrees. Morepreferably, the shoulder angle may be 45 degrees˜55 degrees. Morepreferably, the shoulder angle may be 46 degrees 54 degrees. Morepreferably, the shoulder angle may be 47 degrees˜53 degrees. Morepreferably, the shoulder angle may be 48 degrees˜52 degrees. Morepreferably, the shoulder angle may be 49 degrees˜51 degrees. A shoulderlength may be 40 mm˜130 mm. Preferably, the shoulder length may be 50mm˜120 mm. More preferably, the shoulder length may be 60 mm˜110 mm.More preferably, the shoulder length may be 70 mm˜100 mm. Morepreferably, the shoulder length may be 80 mm˜90 mm.

The constant diameter growth process may refer to a process in which arod-like structure with a diameter determined during the shoulderingprocess may be obtained. In some embodiments, the diameter of thecrystal growth may be 10 mm˜200 mm. Preferably, the length of theconstant diameter of the crystal growth may be 20 mm˜180 mm. Morepreferably, the length of the constant diameter of the crystal growthmay be 50 mm˜150 mm. More preferably, the length of the constantdiameter of the crystal growth may be 60 mm˜140 mm. More preferably, thelength of the constant diameter of the crystal growth may be 70 mm˜130mm. More preferably, the length of the constant diameter of the crystalgrowth may be 80 mm˜120 mm. More preferably, the length of the constantdiameter of the crystal growth may be 90 mm˜110 mm.

The ending process may refer to a process in which the crystal may beraised up to be separated from the melt when the crystal grows to apredetermined length. The ending process may be a reverse operation ofthe shouldering process. The diameter of the crystal may be reduceduntil the crystal is separated from the melt by changing a pulling speedof the pulling rod, or the diameter of the crystal may be reduced to apreset diameter such as 10 mm. An automatic control program may be usedto calculate a change of the diameter of the crystal based on apredetermined parameter of the ending process, and perform the endingprocess according to a preset angle by increasing or decreasing thetemperature. In some embodiments, an ending angle may be 30 degrees˜70degrees. Preferably, the ending angle may be 40 degrees˜60 degrees. Morepreferably, the ending angle may be 45 degrees˜55 degrees. Morepreferably, the ending angle may be 46 degrees˜54 degrees. Morepreferably, the ending angle may be 47 degrees˜53 degrees. Morepreferably, the ending angle may be 48 degrees˜52 degrees. Morepreferably, the ending angle may be 49 degrees˜51 degrees. An endinglength of the crystal may be 40 mm˜110 mm. More preferably, the endinglength of the crystal may be 50 mm˜100 mm. More preferably, the endinglength of the crystal may be 60 mm˜90 mm. More preferably, the endinglength of the crystal may be 70 mm˜80 mm.

The cooling process may refer to a process in which a temperature may beslowly decreased after the ending process is completed, to eliminate astress within the crystal, which may be formed in the high-temperaturecrystal growth. According to a crystal growth method of the presentdisclosure, an annealing operation may be performed on the crystalduring the cooling process. By introducing an oxygen-rich flowing gasinto the crystal growth device, on one hand, a volatilization of SiO2may be reduced and a poor performance consistency of the crystal causedby the composition deviation during the crystal growth may be avoided;on the other hand, an oxygen-deficient condition would not occur duringthe crystal growth, thereby reducing crystal lattice distortion causedby occurrence of oxygen vacancies in the crystal. In this case, theannealing operation can be performed during the crystal growth,accordingly, it is not necessary to perform the annealing operationafter the crystal growth. In some embodiments, when the temperaturedrops to 1400° C.˜800° C., the volume ratio of oxygen in the flowing gasmay be increased to cause the oxygen to effectively diffuse into thecrystal. In some embodiments, during increasing the volume ratio ofoxygen, a cooling rate of the crystal may also be slowed, or a stepwisecooling process may be performed to cause the oxygen to diffuse morefully. In some embodiments, when the flowing gas includes a mixed gas ofoxygen and one or more of nitrogen and inert gas and the temperaturedrops to 1400° C.˜800° C., the volume of oxygen in the flowing gas maybe increased to 1%-30% during the cooling process. Preferably, when thetemperature drops to 1400° C.˜800° C., the volume ratio of oxygen in theflowing gas may be increased to 2%˜28%. More preferably, when thetemperature drops to 1400° C.˜800° C., the volume ratio of oxygen in theflowing gas may be increased to 5%˜25%. More preferably, when thetemperature drops to 1400° C.˜800° C., the volume ratio of oxygen in theflowing gas may be increased to 10%˜20%. More preferably, when thetemperature drops to 1400° C.˜800° C., the volume ratio of oxygen in theflowing gas may be increased to 13%˜17%. More preferably, when thetemperature drops to 1400° C.˜800° C., the volume ratio of oxygen in theflowing gas may be increased to 14%˜16%. When the temperature is lowerthan 800° C., the volume ratio of oxygen in the flowing gas may be atleast decreased to a volume ratio of oxygen in a previous crystal growthprocess, which may be 0.001%˜20%. In some embodiments, a cooling time ofthe crystal may be 20 hours˜100 hours. More preferably, the cooling timeof crystal may be 30 hours˜90 hours. More preferably, the cooling timeof the crystal may be 40 hours˜80 hours. More preferably, the coolingtime of the crystal may be 50 hours˜70 hours. More preferably, thecooling time of the crystal may be 55 hours˜65 hours. In someembodiments, assuming that T is the temperature after the endingprocess, a decreasing rate of a crystal temperature during the coolingprocess may be T/(20−100) hours. In some embodiments, the decreasingrate of the crystal temperature may be 15° C./h˜95° C./h. Morepreferably, the decreasing rate of the crystal temperature may be 20°C./h˜65° C./h. More preferably, the decreasing rate of the crystaltemperature may be 23° C./h˜47° C./h. More preferably, the decreasingrate of the crystal temperature may be 26° C./h˜38° C./h. Morepreferably, the decreasing rate of the crystal temperature may be 28°C./h˜34° C./h. When an output heating power (e.g., the heating power ofthe induction coil) is 0, the crystal growth may end.

The crystal removing process may refer to a process in which the growncrystal may be taken out from the crystal growth device when an internaltemperature of the crystal growth device drops to the room temperature.In the crystal growth process, according to a setting of various processparameters in different stages of the crystal growth process, a growthrate of the crystal may be 0.01 mm/h˜6 mm/h. Preferably, the growth rateof the crystal may be 0.1 mm/h˜6 mm/h. More preferably, the growth rateof the crystal may be 1 mm/h˜6 mm/h. More preferably, the growth rate ofthe crystal may be 2 mm/h˜5 mm/h. More preferably, the growth rate ofthe crystal may be 3 mm/h˜4 mm/h. A diameter of an obtained crystal maybe 50 mm˜115 mm. A diameter of a grown crystal may be equal to orgreater than 60 mm, such as 60 mm˜100 mm (e.g., 60 mm), 70 mm˜100 mm(e.g., 95 mm). A constant diameter may be reached to more than 180 mm,such as 180 mm˜200 mm, 200 mm, 190 mm, or 195 mm˜200 mm.

In some embodiments, one or more processes in the crystal growth may becontrolled by a PID controller. The one or more process may include butare not limited to the necking process, the shouldering process, theconstant diameter growth process, the ending process, the coolingprocess, etc. In some embodiments, a PID parameter may be 0.1˜5.Preferably, the PID parameter may be 0.5˜4.5. More preferably, the PIDparameter may be 1˜4. More preferably, the PID parameter may be 1.5˜3.5.More preferably, the PID parameter may be 2˜3. More preferably, the PIDparameter may be 2.5˜3.5.

It should be noted that the embodiments mentioned above are only used toillustrate the technical solutions of the present disclosure but not tolimit the technical solutions. Various modifications to the disclosedembodiments will be readily apparent to those skilled in the art, andthe general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the present disclosure. Thus, the present disclosure is not limitedto the embodiments shown, but to be accorded the widest scope consistentwith the claims.

FIG. 2 is a schematic diagram illustrating an exemplary temperaturefield device according to some embodiments of the present disclosure. Itshould be noted that FIG. 2 is provided for illustration purposes anddoes not limit the shape and/or structure of the temperature fielddevice. The temperature field device 200 may be mounted in a crystalgrowth device to provide temperature gradient for crystal growth andensure the stability of a crystallization process of the crystal. Asshown in FIG. 2, the temperature field device 200 may include a bottomplate 202, a first drum 204, a second drum 206, a filler 208, a firstcover plate 210, a second cover plate 212, a heater 226, an observationunit 218, a sealing ring 220, a pressure ring 222, and a gas channel224. The temperature field device 200 may be placed in the crystalgrowth device such as a single crystal growth furnace. Specifically, thetemperature field device 200 may be placed in an induction coil 216 inthe single crystal growth, the crucible 214 may be placed in thetemperature field device 200, and the heater 226 may be mounted abovethe crucible 214.

The bottom plate 202 may be mounted on a bottom of the temperature fielddevice 200 to support other components of the temperature field device200, for example, the first drum 204, the second drum 206, the filler208, etc. In some embodiments, a material of the bottom plate 202 mayinclude a heat reflective material with a relatively high reflectioncoefficient, for example, gold, silver, nickel, aluminum foil, copper,molybdenum, coated metal, stainless steel, or the like, or anycombination thereof. Preferably, the bottom plate 202 may include acopper plate. In some embodiments, a diameter of the bottom plate 202may be 200 mm˜500 mm. Preferably, the diameter of the bottom plate 202may be 250 mm˜450 mm. More preferably, the diameter of the bottom plate202 may be 300 mm˜400 mm. More preferably, the diameter of the bottomplate 202 may be 310 mm˜390 mm. More preferably, the diameter of thebottom plate 202 may be 320 mm˜380 mm. More preferably, the diameter ofthe bottom plate 202 may be 430 mm˜370 mm. More preferably, the diameterof the bottom plate 202 may be 440 mm˜360 mm. In some embodiments, athickness of bottom plate 202 may be 10 mm˜40 mm. Preferably, thethickness of the bottom plate 202 may be 15 mm˜35 mm. More preferably,the thickness of the bottom plate 202 may be 20 mm˜30 mm. Morepreferably, the thickness of the bottom plate 202 may be 21 mm˜29 mm.More preferably, the thickness of the bottom plate 202 may be 22 mm˜28mm. More preferably, the thickness of the bottom plate 202 may be 23mm˜27 mm. More preferably, the thickness of the bottom plate 202 may be24 mm˜26 mm. Since the temperature field device 200 may be placed in afurnace body of the single crystal growth furnace, the bottom plate 202may be placed or mounted on a mounting plate of the furnace body. A modeof placing or mounting the bottom plate 202 may include a welding mode,a riveting mode, a bolting mode, a bonding mode, or the like, or anycombination thereof. A level of the bottom plate 202 may be less than0.5 mm/m. Preferably, the level of the bottom plate 202 may be less than0.4 mm/m. More preferably, the level of the bottom plate 202 may be lessthan 0.3 mm/m. More preferably, the level of the bottom plate 202 may beless than 0.2 mm/m. More preferably, the level of the bottom plate 202may be less than 0.1 mm/m. More preferably, level of the bottom plate202 may be less than 0.09 mm/m. More preferably, the level of the bottomplate 202 may be less than 0.08 mm/m. More preferably, the level of thebottom plate 202 may be less than 0.07 mm/m. More preferably, the levelof the bottom plate 202 may be less than 0.06 mm/m. More preferably, thelevel of the bottom plate 202 may be less than 0.05 mm/m. Morepreferably, the level of the bottom plate 202 may be less than 0.04mm/m. More preferably, the level of the bottom plate 202 may be lessthan 0.03 mm/m. More preferably, the level of the bottom plate 202 maybe less than 0.02 mm/m. More preferably, the level of the bottom plate202 may be less than 0.01 mm/m. When the temperature field device 200 isused, an internal temperature may reach a relatively high temperature,for example, 1900° C. Therefore, it is necessary to reduce heatradiation of the temperature field device 200 to prevent the furnacebody from being damaged by excessive heat. In this case, the bottomplate 202 may be provided with channel(s) for circulation cooling fluid,circulation cooling fluid which may be used to absorb the heat insidethe temperature field device 200, thereby insulating the heat andreducing the heat radiation. The channel(s) may be mounted inside thebottom plate 202 with a spiral shape or a snake shape. The coolingliquid may include water, ethanol, ethylene glycol, isopropyl alcohol,n-hexane or the like, or any combination thereof. Merely by way ofexample, the cooling liquid may include a 50:50 mixed liquid of waterand ethanol. A count of the circulating cooling liquid channel(s) may beone or more, for example, 1˜3. In some embodiments, diameter(s) of thecirculating cooling liquid channel(s) may be 5 mm˜25 mm. Preferably, thediameter(s) of the circulating cooling liquid channel(s) may be 10 mm˜20mm. More preferably, the diameter(s) of the circulating cooling liquidchannel(s) may be 11 mm˜19 mm. More preferably, the diameter(s) of thecirculating cooling liquid channel(s) may be 12 mm˜18 mm. Morepreferably, the diameter(s) of the circulating cooling liquid channel(s)may be 13 mm˜17 mm. More preferably, the diameter(s) of the circulatingcooling liquid channel(s) may be 14 mm˜15 mm.

The first drum 204 may be mounted on the bottom plate 202 and constitutean outer wall of the temperature field device 200. The bottom plate 202may cover an open end of the first drum 204. The first drum 204 may bemounted on the bottom plate 202 via a welding mode, a riveting mode, abolting mode, a bonding mode, or the like, or any combination thereof,to support the temperature field device 200. The first drum 204 mayachieve the sealing and the heat preservation of the temperature fielddevice 200 together with other components (e.g., the bottom plate 202,the first cover plate 210) of the temperature field device 200. When thefirst drum 204 is being mounted, a concentricity of the first drum 204and the bottom plate 202 may be less than 1 mm. Preferably, theconcentricity of the first drum 204 and the bottom plate 202 may be lessthan 0.9 mm. More preferably, the concentricity of the first drum 204and the bottom plate 202 may be less than 0.8 mm. More preferably, theconcentricity of the first drum 204 and the bottom plate 202 may be lessthan 0.7 mm. More preferably, the concentricity of the first drum 204and the bottom plate 202 may be less than 0.6 mm. More preferably, theconcentricity of the first drum 204 and the bottom plate 202 may be lessthan 0.5 mm. More preferably, the concentricity of the first drum 204and the bottom plate 202 may be less than 0.4 mm. More preferably, theconcentricity of the first drum 204 and the bottom plate 202 may be lessthan 0.3 mm. More preferably, the concentricity of the first drum 204and the bottom plate 202 may be less than 0.2 mm. More preferably, theconcentricity of the first drum 204 and the bottom plate 202 may be lessthan 0.1 mm. A perpendicularity of the first drum 204 and the bottomplate 202 may be less than 0.2 degrees. Preferably, the perpendicularityof the first drum 204 and the bottom plate 202 may be less than 0.15degrees. More preferably, the perpendicularity of the first drum 204 andthe bottom plate 202 may be less than 0.1 degrees. More preferably, theperpendicularity of the first drum 204 and the bottom plate 202 may beless than 0.05 degrees. More preferably, the perpendicularity of thefirst drum 204 and the bottom plate 202 may be less than 0.03 degrees.In some embodiments, the first drum 204 may be made of quartz, alumina(e.g., corundum), zirconia, graphite, carbon fiber, or the like, or anycombination thereof. According to a size of the bottom plate 202, aninner diameter of the first drum 204 may be 180 mm˜450 mm. Preferably,the inner diameter of the first drum 204 may be 200 mm˜430 mm. Morepreferably, the inner diameter of the first drum 204 may be 220 mm˜410mm. More preferably, the inner diameter of the first drum 204 may be 250mm˜380 mm. More preferably, the inner diameter of the first drum 204 maybe 270 mm˜360 mm. More preferably, the inner diameter of the first drum204 may be 300 mm˜330 mm. More preferably, the inner diameter of thefirst drum 204 may be 310 mm˜320 mm. In some embodiments, a thickness ofthe first drum 204 be 1 mm˜15 mm. Preferably, the thickness of the firstdrum 204 be 3 mm˜12 mm. More preferably, the thickness of the first drum204 be 5 mm˜10 mm. More preferably, the thickness of the first drum 204be 6 mm˜9 mm. More preferably, the thickness of the first drum 204 be 7mm˜8 mm. A height of the first drum 204 may be 600 mm˜1600 mm.Preferably, the height of the first drum 204 may be 700 mm˜1500 mm. Morepreferably, the height of the first drum 204 may be 800 mm˜1400 mm. Morepreferably, the height of the first drum 204 may be 900 mm˜1300 mm. Morepreferably, the height of the first drum 204 may be 1000 mm˜1200 mm.More preferably, the height of the first drum 204 may be 1050 mm˜1150mm. More preferably, the height of the first drum 204 may be 1060mm˜1140 mm. More preferably, the height of the first drum 204 may be1070 mm˜1130 mm. More preferably, the height of the first drum 204 maybe 1080 mm˜1120 mm. More preferably, the height of the first drum 204may be 1090 mm˜1110 mm. More preferably, the height of the first drum204 may be 1095 mm˜105 mm. The second drum 206 may be mounted in thefirst drum 204. In some embodiments, the second drum 206 may be made ofa material with relatively good heat resistance to maintain atemperature of the crystal growth stable. The second drum 206 may bemade of zirconia, alumina, graphite, ceramics, etc. More preferably, thesecond drum 206 may include a zirconium tube made of zirconia. To matchwith the size of the first drum 204, an inner diameter of the seconddrum 206 may be 70 mm˜300 mm. Preferably, the inner diameter of thesecond drum 206 may be 100 mm˜270 mm. More preferably, the innerdiameter of the second drum 206 may be 120 mm˜250 mm. More preferably,the inner diameter of the second drum 206 may be 150 mm˜220 mm. Morepreferably, the inner diameter of the second drum 206 may be 170 mm˜200mm. More preferably, the inner diameter of the second drum 206 may be180 mm˜270 mm. A thickness of the second drum 206 may be 8 mm˜30 mm.Preferably, the thickness of the second drum 206 may be 10 mm˜30 mm.More preferably, the thickness of the second drum 206 may be 12 mm˜30mm. More preferably, the thickness of the second drum 206 may be 15mm˜25 mm. More preferably, the thickness of the second drum 206 may be16 mm˜24 mm. More preferably, the thickness of the second drum 206 maybe 17 mm˜23 mm. More preferably, the thickness of the second drum 206may be 18 mm˜22 mm. More preferably, the thickness of the second drum206 may be 19 mm˜21 mm. In some embodiments, an end of the second drum206 may be placed or mounted on the bottom plate 202, for example, via abonding connection, a welding connection, a riveting connection, a keyconnection, a bolting connection, a buckle connection, or the like, orany combination thereof. A concentricity of the second drum 206 and thebottom plate 202 may be less than 1 mm. Preferably, the concentricity ofthe second drum 206 and the bottom plate 202 may be less than 0.9 mm.More preferably, the concentricity of the second drum 206 and the bottomplate 202 may be less than 0.8 mm. More preferably, the concentricity ofthe second drum 206 and the bottom plate 202 may be less than 0.7 mm.More preferably, the concentricity of the second drum 206 and the bottomplate 202 may be less than 0.6 mm. More preferably, the concentricity ofthe second drum 206 and the bottom plate 202 may be less than 0.5 mm.More preferably, the concentricity of the second drum 206 and the bottomplate 202 may be less than 0.4 mm. More preferably, the concentricity ofthe second drum 206 and the bottom plate 202 may be less than 0.3 mm.More preferably, the concentricity of the second drum 206 and the bottomplate 202 may be less than 0.2 mm. More preferably, the concentricity ofthe second drum 206 and the bottom plate 202 may be less than 0.1 mm. Aperpendicularity of the second drum 206 may be less than 0.2 degrees.Preferably, the perpendicularity of the second drum 206 may be less than0.15 degrees. More preferably, the perpendicularity of the second drum206 may be less than 0.1 degree. More preferably, the perpendicularityof the second drum 206 may be less than 0.08 degrees. More preferably,the perpendicularity of the second drum 206 may be less than 0.05degrees. In some embodiments, when the second drum 206 is mounted on thebottom plate 202, according to different heights, the second drum 206may be in different mounting states. When the height of the second drum206 is the same as that of the first drum 204, the mounting state of thesecond drum 206 may be similar to that of the first drum 204, that is,an open end of the second drum 206 may be connected to the bottom plate202 and the other open end may be connected to the first cover plate210. When the height of the second drum 206 is less than that of thefirst drum 204, the other open end of the second drum 206 may beconnected to other components (e.g., the second cover plate 212) of thetemperature field device 200. The second cover plate 212 may cover theother open end of the second drum 206. Meanwhile, a size and/or a shape(e.g., a diameter of a circle cover plate) of the second cover plate 212may match a cross section of the first drum 204 to achieve a seamlessconnection with the first drum 204. In some embodiments, the second drum206 may not be mounted on the bottom plate 202. When the height of thesecond drum 206 is less than that of the first drum 204, an end of thesecond drum 206 may be mounted on other components (e.g., the firstcover plate 210, the second cover plate 212) of the temperature fielddevice 200, and the other end of the second drum 206 may be kept at acertain distance from the bottom plate 202 (e.g., in a floating state).In some embodiments, the height of the second drum 206 may be same asthe height of the first drum 204. The height of the second drum 206 maybe 500 mm˜1500 mm. Preferably, the height of the second drum 206 may be600 mm˜1400 mm. More preferably, the height of the second drum 206 maybe between 700 mm˜1300 mm. More preferably, the height of the seconddrum 206 may be between 800 mm˜1200 mm. More preferably, the height ofthe second drum 206 may be 900 mm˜1100 mm. More preferably, the heightof the second drum 206 may be 950 mm˜1050 mm. More preferably, theheight of the second drum 206 may be 960 mm˜1040 mm. More preferably,the height of the second drum 206 may be 970 mm˜1030 mm. Morepreferably, the height of the second drum 206 may be 980 mm˜1020 mm.More preferably, the height of the second drum 206 may be 990 mm˜1010mm.

The filler 208 may be filled in the second drum 206, and/or a spacebetween the first drum 204 and the second drum 206. The filler 208 maybe configured for heat preservation. In some embodiments, a heightand/or a tightness of the filler 208 may change a position of acomponent (e.g., the crucible 214) supported by the filler 208 and/or aspace volume of the heat dissipation in temperature field device 200.Different stable temperature gradients for different crystal growths maybe obtained by changing the height and/or the tightness of the filler208. The height of the filler 208 may determine a position of a heatingcenter, which may affect the temperature gradient above a melt interfacein a vertical direction. A particle size and/or a tightness of thefiller 208 may determine the heat insulation capacity of the filler 208(e.g., the smaller the particle size is and the larger the tightness is,the stronger the heat insulation capacity and the stability may be),which may affect the temperature gradient below the melt interface inthe vertical direction. Different heights, particle sizes, and/ortightness of the filler 208 may correspond to different temperaturegradients. In some embodiments, when the second drum 206 is cracked, thefiller 208 filled in the space between the first drum 204 and the seconddrum 206 may act as a heat insulation layer to prevent a change causedby a communication between the temperature field device 200 and theexternal environment, which may affect the crystal growth. The heatinsulation layer formed by the filler 208 may maintain the temperaturegradient in the temperature field device 200 in the above-mentioned caseto avoid the sudden change of the temperature. In some embodiments, thefiller 208 may made of heat resistance material. A shape of the filler208 may include granular. The filler 208 may include zircon sand(zirconium silicate compound), zirconia particles, alumina particles,etc. A particle size of the filler 208 may be 5 mesh˜200 mesh.Preferably, the particle size of the filler 208 may be 10 mesh˜190 mesh.More preferably, the particle size of the filler 208 may be 20 mesh˜180mesh. More preferably, the particle size of the filler 208 may be 30mesh˜170 mesh. More preferably, the particle size of the filler 208 maybe 40 mesh˜160 mesh. More preferably, the particle size of the filler208 may be 50 mesh˜150 mesh. More preferably, the particle size of thefiller 208 may be 60 mesh˜140 mesh. More preferably, the particle sizeof the filler 208 may be 70 mesh˜130 mesh. More preferably, the particlesize of the filler 208 may be 80 mesh˜120 mesh. More preferably, theparticle size of the filler 208 may be 90 mesh˜110 mesh. Morepreferably, the particle size of the filler 208 may be 95 mesh˜105 mesh.In some embodiments, the filler 208 may include a substance with a shapeof felt (e.g., a zirconia felt). In some embodiments, the filler 208 mayinclude a mixture of a substance with a shape of granular, a substancewith a shape of brick, and/or a substance with a shape of felt, forexample, a mixture of one or more of the zirconia felt, the zircon sand,the zirconia particles, or the alumina particles.

In some embodiments, the filler 208 filled in the second drum 206 may beused to support the crucible 214 containing the reactants for thecrystal growth. The filler 208 may cover a portion of the crucible 214,for example, a bottom and a side wall of the crucible 214. To preventthe filler 208 from falling into the reactants in the crucible 214, anupper edge of the crucible 214 may be higher than the filling height ofthe filler 208 filled in the second drum 206. In some embodiments, thesecond drum 206 may prevent the filler 208 filled in the space betweenthe first drum 204 and the second drum 206 from falling into thecrucible 214. In some embodiments, the crucible 214 may be made ofiridium (Ir), molybdenum (Mo), tungsten (W), rhenium (Re), graphite (C),tungsten-molybdenum alloy, or the like, or any combination thereof.Preferably, the crucible 214 may be made of iridium. In someembodiments, a diameter of the crucible 214 may be 60 mm˜250 mm.Preferably, the diameter of the crucible 214 may be 80 mm˜220 mm. Morepreferably, the diameter of the crucible 214 may be 100 mm 200 mm. Morepreferably, the diameter of the crucible 214 may be 110 mm˜190 mm. Morepreferably, the diameter of the crucible 214 may be 120 mm˜180 mm. Morepreferably, the diameter of the crucible 214 may be 130 mm˜170 mm. Morepreferably, the diameter of the crucible 214 may be 140 mm˜160 mm. Morepreferably, the diameter of the crucible 214 may be 145 mm˜155 mm. Athickness of the crucible 214 may be 2 mm˜4 mm. Preferably, thethickness of the crucible 214 may be 2.2 mm˜3.8 mm. More preferably, thethickness of the crucible 214 may be 2.5 mm˜3.5 mm. More preferably, thethickness of the crucible 214 may be 2.6 mm 3.4 mm. More preferably, thethickness of the crucible 214 may be 2.7 mm˜3.3 mm. More preferably, thethickness of the crucible 214 may be 2.8 mm˜3.2 mm. More preferably, thethickness of the crucible 214 may be 2.9 mm˜3.1 mm. A height of crucible214 may be 60 mm˜250 mm. Preferably, the height of the crucible 214 maybe 80 mm˜220 mm. More preferably, the height of the crucible 214 may be100 mm˜200 mm. More preferably, the height of the crucible 214 may be110 mm˜190 mm. More preferably, the height of the crucible 214 may be120 mm˜180 mm. More preferably, the height of the crucible 214 may be130 mm˜170 mm. More preferably, the height of the crucible 214 may be140 mm˜160 mm. More preferably, the height of the crucible 214 may be145 mm˜155 mm.

The heater 226 may be mounted above the crucible 214. In someembodiments, the heater 226 may be used to reduce a temperature gradientabove the crucible 214, and prevent cracking of the crystal caused by asudden drop of the temperature. A shape, a size, and/or a height of theheater 226 should meet a temperature gradient for crystal growth and/ora temperature and a temperature gradient for annealing. The heater 226may be disposed at an end of the 214 close to the temperature fielddevice 200. In some embodiments, the heater 226 may be made of iridium(Ir), platinum (Pt), molybdenum (Mo), tungsten (W), graphite (C), or thelike, or any combination thereof. In some embodiments, an outer diameterof the heater 226 may be 60 mm˜260 mm. Preferably, the outer diameter ofthe heater 226 may be 70 mm˜250 mm. More preferably, the outer diameterof the heater 226 may be 80 mm˜240 mm. More preferably, the outerdiameter of the heater 226 may be 90 mm˜230 mm. More preferably, theouter diameter of the heater 226 may be 100 mm˜220 mm. More preferably,the outer diameter of the heater 226 may be 110 mm˜210 mm. Morepreferably, the outer diameter of the heater 226 may be 120 mm˜200 mm.More preferably, the outer diameter of the heater 226 may be 130 mm˜190mm. More preferably, the outer diameter of the heater 226 may be 140mm˜180 mm. More preferably, the outer diameter of the heater 226 may be150 mm˜170 mm. More preferably, the outer diameter of the heater 226 maybe 160 mm˜170 mm. An inner diameter of the heater 226 may be 40 mm˜240mm. Preferably, the inner diameter of the heater 226 may be 50 mm˜230mm. More preferably, the inner diameter of the heater 226 may be 60mm˜220 mm. More preferably, the inner diameter of the heater 226 may be70 mm˜210 mm. More preferably, the inner diameter of the heater 226 maybe 80 mm˜200 mm. More preferably, the inner diameter of the heater 226may be 90 mm˜190 mm. More preferably, the inner diameter of the heater226 may be 100 mm˜180 mm. More preferably, the inner diameter of theheater 226 may be 110 mm˜170 mm. More preferably, the inner diameter ofthe heater 226 may be 120 mm˜160 mm. More preferably, the inner diameterof the heater 226 may be 130 mm˜150 mm. More preferably, the innerdiameter of the heater 226 may be 140 mm˜150 mm. A thickness of theheater 226 may be 2 mm˜10 mm. Preferably, the thickness of the heater226 may be 3 mm˜9 mm. More preferably, the thickness of the heater 226may be 4 mm˜8 mm. More preferably, the thickness of the heater 226 maybe 5 mm˜7 mm. More preferably, the thickness of the heater 226 may be 6mm˜7 mm. A height of the heater 226 may be 2 mm˜200 mm. Preferably, theheight of the heater 226 may be 10 mm˜190 mm. More preferably, theheight of the heater 226 may be 20 mm˜180 mm. More preferably, theheight of the heater 226 may be 30 mm˜170 mm. More preferably, theheight of the heater 226 may be 40 mm˜160 mm. More preferably, theheight of the heater 226 may be 50 mm˜150 mm. More preferably, theheight of the heater 226 may be 60 mm˜140 mm. More preferably, theheight of the heater 226 may be 70 mm˜130 mm. More preferably, theheight of the heater 226 may be 80 mm˜120 mm. More preferably, theheight of the heater 226 may be 90 mm˜110 mm. More preferably, theheight of the heater 226 may be 100 mm˜110 mm.

FIG. 3 is a schematic diagram illustrating a top view of a cross-sectionof an exemplary temperature field device according to some embodimentsof the present disclosure. As shown in FIG. 3, a periphery of thetemperature field device 300 may be the first drum 204. The spacebetween the second drum 206 and the first drum 204 may be filled withthe filler 208. The crucible 214 may be placed in the second drum 206and supported by the filler 208 which may be filled at the bottom of thesecond drum 206. The heater 226 may be mounted above the crucible 214.It can be seen that, from outside to inside, components of thetemperature field device 300 may successively include the first drum204, the filler 208, the second drum 206, the crucible 214, and theheater 226. The above-mentioned components may form a concentric circleand a concentricity may be less than 1 mm. Preferably, the concentricitymay be less than 0.9 mm. More preferably, the concentricity may be lessthan 0.8 mm. More preferably, the concentricity may be less than 0.7 mm.More preferably, the concentricity may be less than 0.6 mm. Morepreferably, the concentricity may be less than 0.5 mm. More preferably,the concentricity may be less than 0.4 mm. More preferably, theconcentricity may be less than 0.3 mm. More preferably, theconcentricity may be less than 0.2 mm. More preferably, theconcentricity may be less than 0.1 mm. The formed concentric circle maybe beneficial for growing the crystal, observing the crystal growth,introducing flowing gas, and pulling up the crystal.

In some embodiments, the crucible 214 may be used as a heater to meltthe reactants contained therein to facilitate subsequent crystal growth.An induction coil (e.g., the induction coil 216 illustrated in FIG. 2)surrounding the outer wall of the first drum 204 may generate analternating magnetic field when an alternating current with a certainfrequency is passed. A closed induced current (i.e., an eddy current)may be generated in a conductor (e.g., crucible 214) caused by theelectromagnetic induction of the alternating magnetic field. The inducedcurrent may be unevenly distributed on a cross section of the conductorand the electrical energy of a high-density current on a surface of theconductor may be converted into heat energy to increase the temperatureof the conductor to melt the reactants. The induction coil 216 mayinclude a coil with 5 turns˜14 turns. Preferably, the induction coil 216may include a coil with 6 turns˜13 turns. More preferably, the inductioncoil 216 may include a coil with 7 turns˜12 turns. More preferably, theinduction coil 216 may include a coil with 8 turns˜11 turns. Morepreferably, the induction coil 216 may include a coil with 9 turns˜10turns. An induction frequency may be 2 kHz˜15 kHz. More preferably, theinduction frequency may be 3 kHz˜14 kHz. More preferably, the inductionfrequency may be 4 kHz˜13 kHz. More preferably, the induction frequencymay be 5 kHz˜12 kHz. More preferably, the induction frequency may be 6kHz˜11 kHz. More preferably, the induction frequency may be 7 kHz˜10kHz. More preferably, the induction frequency may be 8 kHz˜9 kHz. Aninduction rated power of the induction coil 216 may be 20 kW˜60 kW.Preferably, the induction rated power of the induction coil 216 may be20 kW˜50 kW. More preferably, the induction rated power of the inductioncoil 216 may be 35 kW˜45 kW. More preferably, the induction rated powerof the induction coil 216 may be 36 kW˜44 kW. More preferably, theinduction rated power of the induction coil 216 may be 37 kW˜43 kW. Morepreferably, the induction rated power of the induction coil 216 may be38 kW˜42 kW. More preferably, the induction rated power of the inductioncoil 216 may be 39 kW˜41 kW. An inner diameter of a cylinder enclosed bythe induction coil 216 may be 180 mm˜430 mm. Preferably, the innerdiameter of the cylinder enclosed by the induction coil 216 may be 200mm˜410 mm. More preferably, the inner diameter of the cylinder enclosedby the induction coil 216 may be 220 mm˜390 mm. More preferably, theinner diameter of the cylinder enclosed by the induction coil 216 may be240 mm˜370 mm. More preferably, the inner diameter of the cylinderenclosed by the induction coil 216 may be 260 mm˜350 mm. Morepreferably, the inner diameter of the cylinder enclosed by the inductioncoil 216 may be 280 mm˜330 mm. More preferably, the inner diameter ofthe cylinder enclosed by the induction coil 216 may be 220 mm˜390 mm.More preferably, the inner diameter of the cylinder enclosed by theinduction coil 216 may be 300 mm˜310 mm. A height of the cylinderenclosed by the induction coil 216 may be 150 mm˜350 mm. Preferably, theheight of the cylinder enclosed by the induction coil 216 may be 170mm˜330 mm. More preferably, the height of the cylinder enclosed by theinduction coil 216 may be 190 mm˜310 mm. More preferably, the height ofthe cylinder enclosed by the induction coil 216 may be 210 mm˜290 mm.More preferably, the height of the cylinder enclosed by the inductioncoil 216 may be 230 mm˜270 mm. More preferably, the height of thecylinder enclosed by the induction coil 216 may be 250 mm˜260 mm. Insome embodiments, a filling height of the filler 208 may result in thata vertical distance between an upper edge of the crucible 214 and anupper edge of the induction coil 216 is 0 mm˜∓25 mm, wherein “−”represents that the upper edge of the crucible 214 is lower than theupper edge of the induction coil, and “+” represents that the upper edgeof the crucible 214 is higher than the upper edge of the induction coil216. Preferably, the vertical distance between the upper edge of thecrucible 214 and the upper edge of the induction coil 216 may be +2mm˜+23 mm. More preferably, the vertical distance between the upper edgeof the crucible 214 and the upper edge of the induction coil 216 may be+4 mm˜+21 mm. More preferably, the vertical distance between the upperedge of the crucible 214 and the upper edge of the induction coil 216may be +6 mm˜+19 mm. More preferably, the vertical distance between theupper edge of the crucible 214 and the upper edge of the induction coil216 may be +4 mm˜+17 mm. More preferably, the vertical distance betweenthe upper edge of the crucible 214 and the upper edge of the inductioncoil 216 may be +6 mm˜+15 mm. More preferably, the vertical distancebetween the upper edge of the crucible 214 and the upper edge of theinduction coil 216 may be +8 mm˜+13 mm. More preferably, the verticaldistance between the upper edge of the crucible 214 and the upper edgeof the induction coil 216 may be +10 mm˜+11 mm. The temperature gradientof the temperature field device 300 can be adjusted by changing arelative position between the crucible 214 and the induction coil 216.For example, when the crucible 214 is totally within the coil range ofthe induction coil 216, the heat generated by the crucible 214 may berelatively large; whereas, when only a portion of the crucible 214 is inthe coil range of the induction coil 216, the heat generated by thecrucible 214 may be relatively small, accordingly, the heat positionand/or a space size of heat dissipation in temperature field device 300may be determined, and the temperature field device 300 may be furtheraffected.

The first cover plate 210 may be mounted on a top of the temperaturefield device 300, and may be used to seal the temperature field device300 together with other components (e.g., the first drum 204). The firstcover plate 210 may cover the other open end of the first drum 204. Thefirst cover plate 210 may be connected to the first drum 204 via awelding connection, a riveting connection, a bolting connection, abonding connection, or the like, or any combination thereof. Forexample, a silicone sealing ring may be mounted at the joint between thefirst cover plate 210 and the first drum 204, and a screw may be used toscrew and seal them. In some embodiments, the material of the firstcover plate 210 may be similar to that of the bottom plate 202. Thefirst cover plate 210 may be made of a material with a relatively highreflection coefficient, for example, gold, silver, nickel, aluminumfoil, copper, molybdenum, coated metal, stainless steel, or the like, orany combination thereof. Preferably, the second cover plate 212 mayinclude a copper plate. A concentricity of the first cover plate 210 andthe first drum 204 may be less than 0.5 mm. Preferably, theconcentricity of the first cover plate 210 and the first drum 204 may beless than 0.4 mm. More preferably, the concentricity of the first coverplate 210 and the first drum 204 may be less than 0.3 mm. Morepreferably, the concentricity of the first cover plate 210 and the firstdrum 204 may be less than 0.2 mm. More preferably, the concentricity ofthe first cover plate 210 and the first drum 204 may be less than 0.1mm. In some embodiments, a diameter of the first cover plate 210 may be200 mm˜500 mm. More preferably, the diameter of the first cover plate210 may be 250 mm˜450 mm. More preferably, the diameter of the firstcover plate 210 may be 300 mm˜400 mm. More preferably, the diameter ofthe first cover plate 210 may be 310 mm˜390 mm. More preferably, thediameter of the first cover plate 210 may be 320 mm˜380 mm. Morepreferably, the diameter of the first cover plate 210 may be 430 mm˜370mm. More preferably, the diameter of the first cover plate 210 may be440 mm˜360 mm. In some embodiments, a thickness of the first cover plate210 may be 10 mm˜40 mm. Preferably, the thickness of the first coverplate 210 may be 15 mm˜35 mm. Preferably, the thickness of the firstcover plate 210 may be 20 mm˜30 mm. More preferably, the thickness ofthe first cover plate 210 may be 21 mm˜29 mm. More preferably, thethickness of the first cover plate 210 may be 22 mm˜28 mm. Morepreferably, the thickness of the first cover plate 210 may be 23 mm˜27mm. More preferably, the thickness of the first cover plate 210 may be24 mm˜26 mm. In some embodiments, the first cover plate 210 may includeat least two first through holes. The first through-hole may be used topass a gas. For example, the first through-hole may constitute a channelfor the gas to enter and/or exit the temperature field device 300. Thegas may be introduced into the temperature field device 300 through oneor more of the first through holes and the gas may be discharged fromthe remaining first through holes. In some embodiments, the gas mayinclude inert gas. The inert gas may include nitrogen, helium, neon,argon, krypton, xenon, radon, etc. In some embodiments, the gas mayinclude a mixed gas of oxygen and/or carbon monoxide and one or more ofnitrogen and inert gas. According to the characteristics and size of thecrystal to be grown, a flow rate of the flowing gas introduced into thetemperature field device 300 may be 0.01 L/min˜50 L/min. Preferably, theflow rate of the introduced following gas may be 0.1 L/min˜50 L/min.More preferably, the flow rate of the introduced following gas may be 1L/min˜50 L/min. More preferably, the flow rate of the introducedfollowing gas may be 5 L/min˜45 L/min. More preferably, the flow rate ofthe introduced following gas may be 10 L/min˜40 L/min. More preferably,the flow rate of the introduced following gas may be 15 L/min˜35 L/min.More preferably, the flow rate of the introduced gas may be 20 L/min˜30L/min. More preferably, the flow rate of the introduced following gasmay be 21 L/min˜29 L/min. More preferably, the flow rate of theintroduced following gas may be 22 L/min˜28 L/min. More preferably, theflow rate of the introduced following gas may be 23 L/min˜27 L/min. Morepreferably, the flow rate of the introduced following gas may be 24L/min˜26 L/min.

In some embodiments, other components may be mounted on the first coverplate 210. FIG. 4 is a schematic diagram illustrating a top view of anexemplary first cover plate according to some embodiments of the presentdisclosure. As shown in FIG. 4, the first cover plate 210 may includetwo first through holes 410-1 and 410-2 through which a gas may enterand/or exit the temperature field device 200. In some embodiments,diameters of the first through holes 410-1 and 410-2 may be 15 mm˜30 mm.Preferably, the diameters of the first through holes 410-1 and 410-2 maybe 18 mm˜27 mm. More preferably, the diameters of the first throughholes 410-1 and 410-2 may be 20 mm˜25 mm. More preferably, the diametersof the first through holes 410-1 and 410-2 may be 21 mm˜24 mm. Morepreferably, the diameters of the first through holes 410-1 and 410-2 maybe 22 mm˜23 mm. In some embodiments, rotation central axes of the firstthrough holes 410-1 and 410-2 may be perpendicular to the horizontalplane. In some embodiments, the rotation central axes of the firstthrough holes 410-1 and 410-2 may be at an angle of 3 degrees˜20 degreeswith a vertical line of the horizontal plane. Preferably, the rotationcentral axes of the first through holes 410-1 and 410-2 may be at anangle of 5 degrees˜18 degrees with the vertical line of the horizontalplane. More preferably, the rotation central axes of the first throughholes 410-1 and 410-2 may be at an angle of 7 degrees˜15 degrees withthe vertical line of the horizontal plane. More preferably, the centralaxes of rotation of the first through holes 410-1 and 410-2 may be at anangle of 9 degrees˜13 degrees with the vertical line of the horizontalplane. More preferably, the rotation central axes of the first throughholes 410-1 and 410-2 may be at an angle of 11 degrees˜12 degrees withthe vertical line of the horizontal plane. A distance between thecenters of the two through holes may be 70 mm˜150 mm. Preferably, thedistance between the centers of the two through holes may be 80 mm˜140mm. More preferably, the distance between the centers of the two throughholes may be 90 mm˜130 mm. More preferably, the distance between thecenters of the two through holes may be 100 mm˜120 mm. More preferably,the distance between the centers of the two through holes may be 105mm˜115 mm. More preferably, the distance between the centers of the twothrough holes may be 107 mm˜113 mm. More preferably, the distancebetween the centers of the two through holes may be 109 mm˜111 mm.

In some embodiments, an observation unit 218 may be mounted above thefirst through holes 410-1 and 410-2. Since a crystal growth period isrelatively long (e.g., four days˜40 days), a unit through which theinternal situation of the temperature field device 200 can be observedmay be mounted on the temperature field device 200. A user (e.g., aworker in a factory) can observe the growth of the crystal through theobservation unit 218. If an abnormal situation is found, a timelyremedial action can be executed. FIG. 5 is a schematic diagramillustrating an exemplary observation unit according to some embodimentsof the present disclosure. The observation unit 218 may include atubular unit with a closed end and an open end. The observation unit 218may include a first part 510. A size of the first part 510 may bematched with the first through hole 410-1/410-2 of the first cover plate210, thereby realizing a connection between the observation unit 218 andthe first cover plate 210, for example, via a riveting connection, ascrew connection, etc. According to the diameter of the first throughhole 410-1/410-2, a diameter of the first part 510 may be 15 mm˜30 mm.Preferably, the diameter of the first part 510 may be 18 mm˜27 mm. Morepreferably, the diameter of the first part 510 may be 20 mm˜25 mm. Morepreferably, the diameter of the first part 510 may be 21 mm˜24 mm. Morepreferably, the diameter of the first part 510 may be 22 mm˜23 mm. Theobservation unit 218 may further include a second through hole 520. Thesecond through hole 520 may be mounted at any position of a second part530 of the observation unit 218, and communicate with an internalchamber of the observation unit 218. After that the observation unit 218is connected to the first through hole 410-1/410-2, the second throughhole 520 may be used to get gas passing through. In some embodiments, adiameter of the second through hole 520 may be 3 mm˜10 mm. Preferably,the diameter of the second through hole 520 may be 4 mm˜9 mm. Morepreferably, the diameter of the second through hole 520 may be 5 mm˜8mm. More preferably, the diameter of the second through hole 520 may be6 mm˜7 mm. The second part 530 may include a part of the observationunit 218 that is protruded outside the first cover plate 210 after thatthe observation unit 218 is connected to the first through hole410-1/410-2, and its height may be 50 mm˜100 mm. Preferably, the heightof the second part 530 may be 60 mm˜90 mm. More preferably, the heightof the second part 530 may be 70 mm˜80 mm. More preferably, the heightof the second part 530 may be 71 mm˜79 mm. More preferably, the heightof the second part 530 may be 72 mm˜78 mm. More preferably, the heightof the second part 530 may be 73 mm˜77 mm. More preferably, the heightof the second part 530 may be 74 mm˜76 mm. In some embodiments, adiameter of the second part 530 may be 26 mm˜66 mm. Preferably, thediameter of the second part 530 may be 30 mm˜60 mm. More preferably, thediameter of the second part 530 may be 35 mm˜55 mm. More preferably, thediameter of the second part 530 may be 40 mm˜50 mm. More preferably, thediameter of the second part 530 may be 41 mm˜49 mm. More preferably, thediameter of the second part 530 may be 42 mm˜48 mm. More preferably, thediameter of the second part 530 may be 43 mm˜47 mm. More preferably, thediameter of the second part 530 may be 44 mm˜46 mm. The observation unit218 may also include an observation window 540. The observation window540 may be mounted on a top of the observation unit 218, and may be madeof a transparent material, such as quartz, polymethyl methacrylate(PMMA), polystyrene (PS), polycarbonate (PC), or the like, or anycombination thereof. The user (e.g., the worker in the factory) mayobserve an internal situation of the temperature field device 200through the observation window 540.

Similarly, in order to reduce heat radiation emitted above thetemperature field device 200, the first cover plate 210 may be providedwith channel(s) for circulation cooling fluid. As shown in FIG. 4, thefirst cover plate 210 may include a channel 420 for circulation coolingfluid. A cooling liquid may flow through the channel 420. The coolingliquid may include water, ethanol, ethylene glycol, isopropyl alcohol,n-hexane, or the like, or any combination thereof. For example, thecooling liquid may include a 50:50 mixed liquid of water and ethanol.Through cooling liquid inlets 430-1 and/or 430-2, the cooling liquid mayflow into the circulating cooling liquid channels 440-1, 440-2, and440-3, which may be mounted in the first cover plate 210. Afterabsorbing heat dissipated from the temperature field device 200, thecooling liquid may flow out from the cooling liquid outlet 430-3. Thecooling liquid may be returned to the cooling liquid channel 420 throughother channels, and a next cycle may be performed. In some embodiments,the diameter of the circulating cooling liquid channels 440-1, 440-2,and 440-3 may be 5 mm˜25 mm. Preferably, the diameter of the circulatingcooling liquid channels 440-1, 440-2, and 440-3 may be 10 mm˜20 mm. Morepreferably, the diameter of the circulating cooling liquid channels440-1, 440-2, and 440-3 may be 11 mm˜19 mm. More preferably, thediameter of the circulating cooling liquid channels 440-1, 440-2, and440-3 may be 12 mm˜18 mm. More preferably, the diameter of thecirculating cooling liquid channels 440-1, 440-2, and 440-3 may be 13mm˜17 mm. More preferably, the diameter of the circulating coolingliquid channels 440-1, 440-2, 440-3 may be 14 mm and 15 mm.

In some embodiments, the first cover plate 210 may further include athird through hole 450. For example, when the crystal growth is executedbased on the Czochralski technique, a channel (e.g., the third throughhole 450) for entrance and/or exit of the pulling rod 200 into and/orfrom the temperature field device 200 may be mounted on the first coverplate 210. The pulling rod may include an iridium pulling rod. The thirdthrough hole 450 may be mounted at a center of the first cover plate210. A size of the third through hole 450 may be determined based on asize of the pulling rod. In some embodiments, a shape of the thirdthrough hole 450 may be various. The shape of the third through hole 450may include regular, square, rectangle, rhombus, regular triangle, orany other irregular shape. In some embodiments, an area of the thirdthrough hole 450 may be 100 mm²˜3000 mm². Preferably, the area of thethird through hole 450 may be 200 mm²˜2900 mm². More preferably, thearea of the third through hole 450 may be 300 mm²˜2800 mm². Morepreferably, the area of the third through hole 450 may be 400 mm²˜2700mm². More preferably, the area of the third through hole 450 may be 500mm²˜2600 mm². More preferably, the area of the third through hole 450may be 600 mm²˜2500 mm². More preferably, the area of the third throughhole 450 may be 700 mm²˜2400 mm². More preferably, the area of the thirdthrough hole 450 may be 800 mm²˜2300 mm². More preferably, the area ofthe third through hole 450 may be 900 mm²˜2200 mm². More preferably, thearea of the third through hole 450 may be 1000 mm²˜2100 mm². Morepreferably, the area of the third through hole 450 may be 1100 mm²˜2000mm². More preferably, the area of the third through hole 450 may be 1200mm²˜1900 mm². More preferably, the area of the third through hole 450may be 1300 mm²˜1800 mm². More preferably, the area of the third throughhole 450 may be 1400 mm²˜1700 mm². More preferably, the area of thethird through hole 450 may be 1500 mm²˜1600 mm². When the third throughhole 450 is a circular through hole, its diameter may be 25 mm˜30 mm.Preferably, the diameter of the circular through hole may be 26 mm˜29mm. More preferably, the diameter of the circular through hole may be 27mm˜28 mm.

The second cover plate 212 may be mounted in the first drum 204, coverthe open end of the second drum 206 near the first cover plate 210, andmay be connected to the second drum 206 via a welding connection, ariveting connection, a bolting connection, a bonding connection, or thelike, or any combination thereof. In some embodiments, the second coverplate 212 may be made of a material with a relatively good heatpreservation performance to perform the heat preservation function. Thesecond cover plate 212 may include alumina plate, a zirconia plate, aceramic plate, a metal plate, etc. In some embodiments, a diameter ofthe second cover plate 212 may be determined based on the inner diameterof the first drum 204. The second cover plate 212 may fit the inner wallof the first drum 204. The second cover plate 212 may cover one end ofthe second drum 206, thereby preventing the filler 208 filled in thespace between the first drum 204 and the second drum 206 from fallingout and polluting the reactants in the crucible 214. In order to observethe internal situation of the temperature field device 200 from outsidein existence of the second cover plate 212, through holes (also referredto as fourth through holes) corresponding to the through holes (e.g.,the first through hole 410-1/410-2, the third through hole 450) on thefirst cover plate 210 may be mounted on the second cover plate 212.Rotation central axes of the fourth through holes may be the same as orsimilar to that of the first and/or the third through holes. That is,the fourth through holes may be mounted on the second cover plate 212along the rotation central axes of the first and/or third through holes.In some embodiments, diameters of the fourth through holes correspondingto the first through hole 410-1/410-2 may be 8 mm˜15 mm. Preferably, thediameters of the fourth through holes corresponding to the first throughhole 410-1/410-2 may be 9 mm˜14 mm. More preferably, the diameters ofthe fourth through holes corresponding to the first through hole410-1/410-2 may be 10 mm˜13 mm. More preferably, the diameters of thefourth through holes corresponding to the first through hole 410-1/410-2may be 11 mm˜12 mm. The rotation center axes of the fourth through holescorresponding to the first through hole 410-1/410-2 may be at an angleof 3 degrees˜20 degrees with a vertical line of the horizontal plane.Preferably, the rotation center axes of the fourth through holescorresponding to the first through hole 410-1/410-2 may be at an angleof 5 degrees˜18 degrees with the vertical line of the horizontal plane.More preferably, the rotation center axes of the fourth through holescorresponding to the first through hole 410-1/410-2 may be at an angleof 7 degrees˜15 degrees with the vertical line of the horizontal plane.More preferably, the rotation center axes of the fourth through holescorresponding to the first through hole 410-1/410-2 may be at an angleof 9 degrees˜13 degrees with the vertical line of the horizontal plane.More preferably, the rotation center axes of the fourth through holescorresponding to the first through hole 410-1/410-2 may be at an angleof 11 degrees˜12 degrees with the vertical line of the horizontal plane.A distance between centers of the fourth through-holes corresponding tothe first through-holes 410-1/410-2 may be 50 mm˜140 mm. Preferably, thedistance between the centers of the fourth through-holes correspondingto the first through-holes 410-1/410-2 may be 60 mm 130 mm. Morepreferably, the distance between the centers of the fourth through-holescorresponding to the first through-holes 410-1/410-2 may be 70 mm˜120mm. More preferably, the distance between the centers of the fourththrough-holes corresponding to the first through-holes 410-1/410-2 maybe 80 mm˜110 mm. More preferably, the distance between the centers ofthe fourth through-holes corresponding to the first through-holes410-1/410-2 may be 90 mm˜100 mm. More preferably, the distance betweenthe centers of the fourth through-holes corresponding to the firstthrough-holes 410-1/410-2 may be 91 mm˜99 mm. More preferably, thedistance between the centers of the fourth through-holes correspondingto the first through-holes 410-1/410-2 may be 92 mm˜98 mm. Morepreferably, the distance between the centers of the fourth through-holescorresponding to the first through-holes 410-1/410-2 may be 93 mm˜97 mm.More preferably, the distance between the centers of the fourththrough-holes corresponding to the first through-holes 410-1/410-2 maybe 94 mm˜96 mm. In some embodiments, a diameter of a fourth through-holecorresponding to the third through-hole may be 10 mm˜150 mm. Preferably,the diameter of the fourth through-hole corresponding to the thirdthrough-hole may be 20 mm˜140 mm. More preferably, the diameter of thefourth through-hole corresponding to the third through-hole may be 30mm˜130 mm. More preferably, the diameter of the fourth through-holecorresponding to the third through-hole may be 40 mm˜120 mm. Morepreferably, the diameter of the fourth through-hole corresponding to thethird through-hole may be 50 mm˜110 mm. More preferably, the diameter ofthe fourth through-hole corresponding to the third through-hole may be60 mm˜100 mm. More preferably, the diameter of the fourth through-holecorresponding to the third through-hole may be 70 mm˜90 mm. Morepreferably, the diameter of the fourth through-hole corresponding to thethird through-hole may be 75 mm˜85 mm. The diameter of the fourththrough hole corresponding to the third through hole may affect theamount of heat dissipated from it, thereby affecting the temperaturegradient of the temperature field device 200. In this case, thetemperature gradient of the temperature field device 200 may be adjustedby changing the diameter of the fourth through hole corresponding to thethird through hole. In some embodiments, an automatic feeder may bemounted above the fourth through hole corresponding to the first throughhole 410-1/410-2, which can automatically add the reactants to thecrucible 214. In this case, a concentration gradient caused by thereactants during the crystal growth may be constant, thereby improvingthe uniformity and consistency of the crystal growth.

In some embodiments, a thickness of the second cover plate 212 may be 20mm˜35 mm. Preferably, the thickness of the second cover plate 212 may be25 mm˜30 mm. More preferably, the thickness of the second cover plate212 may be 26 mm˜29 mm. More preferably, the thickness of the secondcover plate 212 may be 27 mm˜28 mm. In some embodiments, a position ofthe second cover plate 212 in the temperature field device 200 may bedetermined based on the length and/or the position of the second drum206. When the length of the second drum 206 is greater than a lengththreshold, the second cover plate 212 may be close to the first coverplate 210. A certain distance may be maintained between the second coverplate 212 and the first cover plate 210.

The sealing ring 220 and/or the pressure ring 222 may achieve a sealbetween the first drum 204 and the first cover plate 210. In someembodiments, the sealing ring 220 may be mounted at a joint between thefirst drum 204 and the first cover plate 210, which may made of amaterial having a certain elasticity, for example, silicone, rubber,etc. An inner diameter of the sealing ring 220 may be less than or equalto the outer diameter of the first drum 204, so that when the sealingring 220 is mounted, the sealing ring 220 may be stretched to sealeffectively a gap between the first drum 204 and the first cover plate210. In some embodiments, the inner diameter of the sealing ring 220 maybe 170 mm˜540 mm. Preferably, the inner diameter of the sealing ring 220may be 200 mm˜510 mm. More preferably, the inner diameter of the sealingring 220 may be 250 mm˜350 mm. More preferably, the inner diameter ofthe sealing ring 220 may be 260 mm˜340 mm. More preferably, the innerdiameter of the sealing ring 220 may be 270 mm˜330 mm. More preferably,the inner diameter of the sealing ring 220 may be 280 mm˜320 mm. Morepreferably, the inner diameter of the sealing ring 220 may be 290 mm˜310mm. A thickness of the sealing ring 220 may be 5 mm˜10 mm. Preferably,the wire diameter of the sealing ring 220 may be 6 mm˜9 mm. Morepreferably, the wire diameter of the sealing ring 220 may be 7 mm˜8 mm.

The pressure ring 222 may be configured to perform a fixing andcompressing function for the sealing ring 220. In some embodiments, ashape of the pressure ring 222 may match the shape of the first drum204, and an inner diameter of the pressure ring 222 may be larger thanthe outer diameter of the first drum 204. The pressure ring 222 may benested on the first drum 204 and may be movable. The pressure ring 222may include a threaded hole corresponding to the first cover plate 210.The sealing ring 220 may be mounted between the pressure ring 222 andthe first cover plate 210. The pressure ring 222 may be connected to thefirst cover plate 210 via a thread, thereby compressing the sealing ring220, enlarging a contact surface of the gap between the first drum 204and the first cover plate 210, causing the contact tightly, andperforming an effective sealing function. In some embodiments, one ormore items may be used to perform the sealing function, for example,vacuum grease. The sealing ring 220 may be covered with the vacuumgrease to perform more effective sealing function. In some embodiments,the pressure ring 222 and the first cover plate 210 may also beconnected via a buckle connection. In some embodiments, an outerdiameter of the pressure ring 222 may be 200 mm˜500 mm. Preferably, theouter diameter of the pressing ring 222 may be 250 mm˜450 mm. Morepreferably, the outer diameter of the pressing ring 222 may be 300mm˜400 mm. More preferably, the outer diameter of the pressing ring 222may be 310 mm˜390 mm. More preferably, the outer diameter of thepressure ring 222 may be 320 mm˜380 mm. More preferably, the outerdiameter of the pressing ring 222 may be 430 mm˜370 mm. More preferably,the outer diameter of the pressing ring 222 may be 440 mm˜360 mm. Morepreferably, the outer diameter of the pressing ring 222 may be 345mm˜355 mm. An inner diameter of the pressure ring 222 may be 190 mm˜460mm. Preferably, the inner diameter of the pressing ring 222 may be 220mm˜530 mm. More preferably, the inner diameter of the pressing ring 222may be 250 mm˜400 mm. More preferably, the inner diameter of thepressure ring 222 may be 280 mm˜520 mm. More preferably, the innerdiameter of the pressing ring 222 may be 300 mm˜400 mm. More preferably,the inner diameter of the pressing ring 222 may be 310 mm˜390 mm. Morepreferably, the inner diameter of the pressing ring 222 may be 320mm˜380 mm. More preferably, the inner diameter of the pressure ring 222may be 430 mm˜370 mm. More preferably, the inner diameter of thepressure ring 222 may be 440 mm˜360 mm. More preferably, the innerdiameter of the pressure ring 222 may be 345 mm˜355 mm. A thickness ofthe pressing ring 222 may be 8 mm˜15 mm. More preferably, the thicknessof the pressing ring 222 may be 10 mm˜13 mm. More preferably, thethickness of the pressing ring 222 may be 11 mm˜12 mm.

In some embodiments, the temperature field device 200 may furtherinclude a gas channel 224. The gas channel 224 may be mounted on theobservation unit 218, and a size of the gas channel 224 may match withthat of the through hole 520 to form a through tube protruding from theobservation unit 218. In this case, the gas channel 224 may be connectedto a vent tube to pass the gas into the temperature field device 200.

In some embodiments, the temperature field device 200 may be applied incrystal growth. The reactants for growing crystals may be placed in thecrucible 214 for reaction after being weighed and performed a processingoperation (e.g., a high temperature roasting operation, a roomtemperature mixing operation, an isostatic pressing operation) accordingto a reaction equation for preparing the crystal. Different crystal mayneed different growth conditions, for example, different temperaturegradients. Accordingly, the temperature gradient may be adjusted byadjusting an amount and a tightness of the filler 208 (e.g., the filler208 filled in the second drum 206) filled in the temperature fielddevice 200. For example, the amount of the filler 208 may determine arelative position of the crucible 214 and the induction coil 216, andfurther determine a heating center of the temperature field device 200.The tightness of the filler 208 may improve the heat preservationcapacity of the filler 208 and the stability of the temperature fielddevice 200, which may be beneficial for the crystal growth. After theamount, the particle size, and the tightness of the filler 208 aredetermined, other components may be mounted and sealed. After thecomponents are mounted, a gas may be introduced into the temperaturefield device 200, and an auxiliary component (e.g., a coolingcirculation pump) may be activated to pass a cooling fluid intocirculating cooling liquid channel(s), which may be mounted in thebottom plate 202 and the first cover plate 210. Then, the crystal growthdevice (including the temperature field device 200) may be activated tostart the crystal growth. The gas passing into temperature field device200 may enter from one or more first through holes (e.g., the gaschannels 224). The gas exiting the temperature field device 200 may bedischarged through the remaining first through holes (e.g., the gaschannel 224). After the temperature is adjusted as suitable, anautomatic control program may be started to enter an automatic growthmode, through a necking process, a shouldering process, a constantdiameter growth process, an ending process, and a cooling process, thecrystal growth may be ended after several days (e.g., four days˜40days).

FIG. 6 is a schematic diagram illustrating an exemplary image of a growncrystal according to some embodiments of the present disclosure. Asshown in FIG. 6, a length of the grown rod-like crystal with a constantdiameter is 150 mm and a diameter of the grown crystal is 93 mm. Thecrystal has a complete appearance, no cracks, no clouds, nomisalignment, and no structural defects. A decay time of an LYSO grownaccording to the method disclosed in the present disclosure is 22 ns˜30ns, which may be less than 35 ns˜42 ns of a crystal grown according to aconventional method.

According to the devices and the methods for crystal growth, a newsingle crystal furnace and a temperature gradient device are adopted,and a process, a ration of reactants, and growth parameters are adjustedand optimized, accordingly, a crystal with a short decay time, a highluminous intensity, and a high luminous efficiency can be grown withouta co-doping operation. In addition, excess reactants (e.g., silicondioxide) are used and a following gas is introduced according to themethod, which can reduce or avoid composition deviation caused byvolatility of the reactants during the growth process and improve thecrystal performance consistency and growth repeatability. Further, animproved temperature field device can provide a temperature field withgood temperature gradient and good uniformity for the growth of crystal,which may reduce crack of the crystal. By optimizing the parameters ofthe crystal growth process, the crystal performance consistency isimproved. It should be noted that different embodiments may havedifferent beneficial effects. In different embodiments, the possiblebeneficial effects may have one or more above described beneficialeffects, or any other beneficial effect.

EXAMPLE

The present disclosure may be further described according to thefollowing embodiments.

Example 1—The Installation of the Temperature Field Device 200

In step 1, the bottom plate 202 may be mounted on an aluminum plate of acrystal growth device. A level of the bottom plate 202 may be adjustedto 0.02 mm/m.

In step 2, the second drum 206 may be mounted on the bottom plate 202,and a concentricity and a verticality between the second drum 206 andbottom plate 202 may be adjusted. The concentricity between the seconddrum 206 and the bottom plate 202 may be less than 0.5 mm and theperpendicularity between the second drum 206 and the bottom plate 202may be less than 0.2 degrees.

In step 3, the first drum 204 may be mounted on the bottom plate 202,and a concentricity and a verticality between the first drum 204 andbottom plate 202 may be adjusted. The concentricity between the firstdrum 204 and the bottom plate 202 may be less than 0.5 mm and theperpendicularity between the first drum 204 and the bottom plate 202 maybe less than 0.2 degrees. A high-temperature adhesive may be used toseal a joint between the first drum 204 and the bottom plate 202,thereby ensuring a positive pressure and avoiding gas leakage.

In step 4, the filler 208 may be filled in the space between the firstdrum 204 and the second drum 206, and filled in the bottom of the seconddrum 206. An amount and a tightness of the filler 208 may be determinedaccording to a growth condition of the crystal.

In step 5, the crucible 214 may be placed on the filler 208 filled inthe bottom of the second drum 206. A vertical distance between an upperedge of the crucible 214 and an upper edge of the induction coil 216 maybe 0 mm˜25 mm. “−” represents that the upper edge of crucible 214 isbelow the upper edge of induction coil 216, “0” represents that theupper edge of crucible 214 is flush with the upper edge of inductioncoil 216, “+” represents that the upper edge of the crucible 214 ishigher than the upper edge of the induction coil 216. The verticaldistance between the upper edge of the crucible 214 and the upper edgeof the induction coil 216 may be determined according to the growthcondition of the crystal to be grown.

In step 6, the heater 226 may be mounted above the crucible 214.

In step 7, the second cover plate 212 may be mounted above the seconddrum 206, and a concentricity among the second cover plate 212, thefirst drum 204, and the second drum 206 may be adjusted.

In step 8, the pressure ring 222 and the sealing ring 220 coated withvacuum grease may be mounted.

In step 9, the first cover plate 210 may be mounted above the first drum204, and a concentricity between the first cover plate 210 and the firstdrum 204 may be adjusted to ensure that the first through hole(s) (e.g.,the first through hole 410-1/410-2) on the first cover plate 210 mayhave the same axis(es) with the fourth through-hole(s) corresponding tothe second cover plate 212. The pressure ring 222 and the first coverplate 210 may be connected via a thread connection and the sealing ring220 may be pressed to achieve the sealing function, ensure a positivepressure, and avoid gas leakage.

In step 10, the observation unit 218 may be mounted on the first coverplate 210 and a vent pipe may be connected to the gas channel 224. Thenthe temperature field device 200 would be installed.

Example 2—Ce:LSO Crystal Growth

The crystal may be prepared using the Czochralski technique via a mediumfrequency induction heating mode and a single crystal growth inductionfurnace with an open furnace. A temperature field device may be mountedaccording to the steps 1-5 described in Example 1. Reactants with purityof 99.999% may be taken out after a roasting process is performed on thereactants at 1000° C. for 5 hours and the reactants are naturally cooledto room temperature 35° C. The reactants may be weighted based on amolar ratio of the reactants according to the Equation below:(1−x−y)Lu₂O₃+SiO₂+2xCeO₂ +yCe₂O₃→Lu_(2(1-x-y))Ce_(2(x+y))SiO₅ +x/2O₂↑where x=0.15%, y=0.3%, and a weight of SiO₂ may excess of 0.2% of itsweight. After being weighted, the reactants may be placed in athree-dimensional mixer for 0.5 hours˜48 hours, and then taken out andplaced in a pressing mold and pressed into a cylindrical shape by a coldisostatic pressing device with a pressure of 100 MPa˜300 MPa. Thereactants may be placed in an iridium crucible with a diameter of 120 mmand a height of 120 mm. The iridium crucible may be placed in themounted temperature field device. A concentricity between the iridiumcrucible and the temperature field device may be adjusted and a crucibleposition of the iridium crucible may be set as +20 mm. A concentricityamong the iridium crucible 214, the heater 226, the second cover plate212, the first cover plate 210, and the weighing guide rod may besuccessively adjusted. The seal of the first cover plate 210 and thefirst drum 204 may be ensured. After the observation unit 218 is mountedon the first cover plate 210, a flowing gas of N₂ may be introduced intothe temperature field device with a gas flow rate of 30 L/min and acirculating cooling liquid may be introduced into the temperature fielddevice. Parameters of the crystal growth may be set. For example, adiameter of the crystal may be set as 60 mm, a shoulder length may beset as 60 mm, an constant diameter may be set as 200 mm, an endinglength may be set as 30 mm, a heating time may be set as 24 hours, arotation rate may be set as 10 rpm, a pulling rate may be set as 2 mm/h,a cooling time may be set as 60 hours, a PID value may be set as 0.5, acrystal density may be set as 7.4 g/cm³, and a melt density may be setas 6.3 g/cm³. After the parameters are set, a seed crystal of Ce:LSO maybe placed on a top of a pulling rod which may be connected to a weighingguide rod and a concentricity between the seed crystal and the firstcover plate 210 may be adjusted. The temperature may be increased tomelt the reactants. During rising temperature, the seed crystal may bedropped for preheating. To avoid cracking of seed crystal, a distancebetween the seed crystal and a surface of the reactants may be kept as 5mm˜15 mm. After the reactants are melt, the seed crystal may be droppedto contact the melt and the temperature may be adjusted. Duringadjusting the temperature, the seed crystal may be sunk 2 mm toeffectively contact with the melt, ensure interface integrity, andreduce crystal cracking caused by a seeding point during a subsequentcooling process. After the temperature is adjusted as suitable, anautomatic control program may be started to enter an automatic growthmode. After a necking process, a shouldering process, a constantdiameter growth process, an ending process, and a cooling process, thecrystal growth may end after 11 days.

A color of the crystal is white, a shape of the crystal is normal as apreset shape, a surface of the crystal is rough, and there is a slightmelt back strip. After a head and a tail of the crystal are removed andthe remaining portions are polished, an interior of the crystal istransparent. The crystal has no macro defects such as point scattering,a cloud layer, a wrapping material, etc. Through a testing process, thelattice parameters of the crystal are a=1.4254 nm, b=0.6641 nm, c=1.0241nm, and β=122° 12″. A transmittance of the crystal from ultraviolet,visible light, to near-infrared band is greater than 80%. A centerwavelength of the crystal is 420 nm, a light yield is greater than orequal to 58000 photons/megaelectron electron volt, an energy resolutionmay be less than or equal to 6.5%, and an decay time is less than orequal to 35 nanoseconds.

Example 3—Ce:LYSO Crystal Growth

The crystal may be prepared using the Czochralski technique via a mediumfrequency induction heating mode and a single crystal growth inductionfurnace with an open furnace. A temperature field device may be mountedaccording to the steps 1˜6. Reactants with purity of 99.999% may betaken out after a roasting process is performed on the reactants at1200° C. for 5 hours and the reactants are naturally cooled to roomtemperature 35° C. The reactants may be weighted based on a molar ratioof the reactants according to Equation below:(1−x−y−z)Lu₂O₃ +zY₂O₃+SiO₂+2xCeO₂+yCe₂O₃→Lu_(2(1-x-y-z))Y_(2z)Ce_(2(x+y))SiO₅ +x/2O₂↑  (2)where, x=0.16%, y=0.3%, z=20%, and a weight of SiO₂ may excess of 2% ofits weight. After being weighted, the reactants may be placed in athree-dimensional mixer for 1 hours˜6 hours, and then taken out andplaced in a pressing mold and pressed into a cylindrical shape by a coldisostatic pressing device with a pressure of 200 MPa. The reactants maybe placed in an iridium crucible with a diameter of 180 mm and a heightof 180 mm. The iridium crucible may be placed in the installedtemperature field device. A concentricity between the iridium crucibleand the temperature field device may be adjusted and a crucible positionof the iridium crucible may be set as +20 mm. A concentricity among theiridium crucible 214, the heater 226, the second cover plate 212, thefirst cover plate 210, and the weighing guide rod may be successivelyadjusted. The seal of the first cover plate 210 and the first drum 204may be ensured. After the observation unit 218 is mounted on the firstcover plate 210, a flowing gas of N₂ may be introduced into thetemperature field device with a gas flow rate of 30 L/min and acirculating cooling liquid may be introduced into the temperature fielddevice. Parameters of the crystal growth may be set. For example, adiameter of the crystal may be set as 95 mm, a shoulder length may beset as 95 mm, a constant diameter may be set as 200 mm, an ending lengthmay be set as 70 mm, a heating time may be set as 24 hours, a rotationrate may be set as 10 rpm, a pulling rate may be set as 1.5 mm/h, acooling time may be set as 100 hours, a PID value may be set as 0.5, acrystal density may be set as 7.25 g/cm³, and a melt density may be setas 6.15 g/cm³. After the parameters are set, a seed crystal of Ce:LYSOmay be placed on a top of a pulling rod which may be connected to aweighing guide rod and a concentricity between the seed crystal and thefirst cover plate 210 may be adjusted. The temperature may be increasedto melt the reactants and during the increasing of the temperature, theseed crystal may be dropped for preheating. To avoid cracking of seedcrystal, a distance between the seed crystal and a surface of thereactants may be kept as 5 mm˜15 mm. After the reactants are melt, theseed crystal may be dropped to contact with the melt and the temperaturemay be adjusted. During the adjusting of the temperature, the seedcrystal may be sunk 2 mm to effectively contact with the melt, duringwhich the interface is integral, thereby reducing crystal crackingcaused by a seeding point during a subsequent cooling process. After thetemperature is adjusted as suitable, an automatic control program may bestarted to enter an automatic growth mode to enter a necking process, ashouldering process, a constant diameter growth process, an endingprocess, and a cooling process. The crystal growth may end after 16days.

A color of the crystal is white, a shape of the crystal is normal as apreset shape, a surface of the crystal is rough, and there is a slightmelt back strip. After a head and a tail of the crystal are removed andthe remaining portions are polished, an interior of the crystal istransparent. The crystal has no macro defects such as point scattering,a cloud layer, a wrapping material, etc. Through a testing process, thelattice parameters of the crystal are a=1.4254 nm, b=0.6641 nm, c=1.0241nm, and β=122.2°. A transmittance of the crystal from ultraviolet,visible light, to near-infrared band is greater than 80%. A centerwavelength of the crystal is 420 nm, a light yield is greater than orequal to 60000 photons/megaelectron electron volt, an energy resolutionis less than or equal to 6%, and a decay time is less than or equal to30 nanoseconds.

It should be noted that the above description for the basic concepts ismerely provided for the purposes of illustration, and not intended tolimit the scope of the present disclosure. For persons having ordinaryskills in the art, multiple variations and modifications may be madeunder the teachings of the present disclosure. However, those variationsand modifications do not depart from the scope of the presentdisclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be combined assuitable in one or more embodiments of the present disclosure.

Furthermore, the recited order of processing elements or sequences, orthe use of numbers, letters, or other designations therefore, is notintended to limit the claimed processes and methods to any order exceptas may be specified in the claims. Although the above disclosurediscusses through various examples what is currently considered to be avariety of useful embodiments of the disclosure, it is to be understoodthat such detail is solely for that purpose, and that the appendedclaims are not limited to the disclosed embodiments, but, on thecontrary, are intended to cover modifications and equivalentarrangements that are within the spirit and scope of the disclosedembodiments. For example, although the implementation of variouscomponents described above may be embodied in a hardware device, it mayalso be implemented as a software only solution, e.g., an installationon an existing server or mobile device.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure aiding in theunderstanding of one or more of the various inventive embodiments. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the claimed subject matter requires more features thanare expressly recited in each claim. Rather, inventive embodiments liein less than all features of a single foregoing disclosed embodiment.

In some embodiments, the numbers expressing quantities, properties, andso forth, used to describe and claim certain embodiments of theapplication are to be understood as being modified in some instances bythe term “about,” “approximate,” or “substantially.” For example,“about,” “approximate,” or “substantially” may indicate ±20% variationof the value it describes, unless otherwise stated. Accordingly, in someembodiments, the numerical parameters set forth in the writtendescription and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by aparticular embodiment. In some embodiments, the numerical parametersshould be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques. Notwithstandingthat the numerical ranges and parameters setting forth the broad scopeof some embodiments of the application are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspracticable.

Each of the patents, patent applications, publications of patentapplications, and other material, such as articles, books,specifications, publications, documents, things, and/or the like,referenced herein is hereby incorporated herein by this reference in itsentirety for all purposes, excepting any prosecution file historyassociated with same, any of same that is inconsistent with or inconflict with the present document, or any of same that may have alimiting affect as to the broadest scope of the claims now or laterassociated with the present document. By way of example, should there beany inconsistency or conflict between the description, definition,and/or the use of a term associated with any of the incorporatedmaterial and that associated with the present document, the description,definition, and/or the use of the term in the present document shallprevail.

In closing, it is to be understood that the embodiments of theapplication disclosed herein are illustrative of the principles of theembodiments of the application. Other modifications that may be employedmay be within the scope of the application. Thus, by way of example, butnot of limitation, alternative configurations of the embodiments of theapplication may be utilized in accordance with the teachings herein.Accordingly, embodiments of the present application are not limited tothat precisely as shown and described.

We claim:
 1. A method for growing a crystal, a formula of the crystalbeing${X_{2x}\text{:}M_{2m}\text{:}{Lu}_{2{({1 - x - m - z})}}Y_{2z}{SiQ}_{({5 - \frac{n}{2}})}N_{n}},$wherein x consists of at least one of Ce, Cl, F, Br, N, P, or S, Mconsists of at least one of Ca, Mg, Sr, Mn, Ba, Al, Fe, Re, La, Ce, Rr,Nd, Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, Yb, Tm, Lu, Sc, or Y, Q consists ofat least one of O, Cl, F, Br, or S, and N consists of at least one ofCl, F, Br, or S, wherein the method comprises: weighting reactantsaccording to a molar ratio of the reactants according to a reactionequation for generating the crystal after a first preprocessingoperation is performed on the reactants, wherein x=0.000001˜0.06,m=0˜0.06, z=0˜1, and n=0˜5, and the first preprocessing operationincludes a roasting operation under 800° C.˜1400° C.; placing reactantson which a second preprocessing operation has been performed into acrystal growth device after an assembly processing operation isperformed on at least one component of the crystal growth device,wherein the second preprocessing operation includes at least one of aningredient mixing operation or a pressing operation at room temperature,the at least one component of the crystal growth device includes acrucible, and the assembly processing operation includes at least one ofa coating operation, an acid soaking and cleaning operation, or animpurity cleaning operation; introducing a flowing gas into the crystalgrowth device after sealing the crystal growth device; and activatingthe crystal growth device to grow the crystal based on the Czochralskitechnique.
 2. The method of claim 1, wherein x at least consists of Ce,and a reactant consisting of Ce includes at least one of CeO₂, Ce₂O₃,Ce(CO₃)₂, CeCl₃, cerium fluoride, cerium(III) sulfate, or cerium(III)bromide.
 3. The method of claim 1, wherein a weight of a reactantconsisting of Si excesses of 0.01 at %˜10 at %, 0.1 at %˜10 at %, 1 at%˜10 at %, 2 at %˜9 at %, or 4 at %˜7 at %.
 4. A method for growing acrystal, comprising: weighting reactants based on a molar ratio of thereactants according to a reaction equation (1) or a reaction equation(2) after a first preprocessing operation is performed on the reactants:(1−x−y)Lu₂O₃+SiO₂+2xCeO₂ +yCe₂O₃→Lu_(2(1-x-y))Ce_(2(x+y))SiO₅+x/2O₂↑  (1)(1−x−y−z)Lu₂O₃ +zY₂O₃+SiO₂+2xCeO₂+yCe₂O₃→Lu_(2(1-x-y-z))Y_(2z)Ce_(2(x+y))SiO₅ +x/2O₂↑  (2) wherex=0.0001%˜6%, m=0−6%, z=0˜1, and a weight of SiO₂ excesses of 0.001%˜10%of its weight, and the first preprocessing operation includes a roastingoperation under 800° C.˜1400° C.; placing reactants on which a secondpreprocessing operation has been performed into a crystal growth deviceafter an assembly preprocessing operation is performed on at least onecomponent of the crystal growth device, wherein the second preprocessingoperation includes at least one of an ingredient mixing operation or apressing operation at room temperature, the at least one component ofthe crystal growth device includes a crucible, and the assemblyprocessing operation includes at least one of a coating operation, anacid soaking and cleaning operation, or an impurity cleaning operation;introducing a flowing gas into the crystal growth device after sealingthe crystal growth device; and activating the crystal growth device togrow the crystal based on the Czochralski technique.
 5. The method ofclaim 4, wherein a weight of SiO₂ excesses of 0.01%˜10%, 0.1%˜10%,1%˜10%, 2%˜9%, or 4%˜7% of its weight.
 6. The method of claim 4, whereinx=0.001%˜6%, 0.01%˜6%, 0.15%˜6%, 1%˜6%, or 2%˜5%.
 7. The method of claim4, wherein y=1%˜5%, 2%˜4%, 2.5%˜3.5%, or 2.8%˜3.2%.
 8. The method ofclaim 4, wherein a purity of each of the reactants is greater than 99%,99.9%, 99.99%, or 99.999%.
 9. The method of claim 4, wherein: theflowing gas includes oxygen or a mixed gas of oxygen and one or more ofnitrogen and inert gas.
 10. The method of claim 4, wherein a meltingtime of a heat treatment for melting the reactants is 5 hours˜48 hoursduring the crystal growth.
 11. The method of claim 4, wherein a distancebetween a seed crystal and an upper surface of the reactants is 5˜100 mmduring melting the reactants during the crystal growth.
 12. The methodof claim 4, wherein the method comprises: sinking a seed crystal to 0.1mm˜50 mm below a surface of a melt of the reactants by controlling apulling rod during temperature adjustment.
 13. The method of claim 4,wherein the method further comprise: maintaining a constant temperatureat 1950° C.˜2150° C. for at least 0.1 hours˜1 hour after temperatureadjustment.
 14. The method of claim 4, wherein a rotation rate of apulling rod is 0.01 r/min˜35 r/min during the crystal growth.
 15. Themethod of claim 4, wherein a growth rate of the crystal is 0.01 mm/h˜6mm/h during the crystal growth.
 16. The method of claim 4, wherein atemperature decreasing time of the crystal during the crystal growth is20 hours˜100 hours.
 17. The method of claim 4, wherein, a volume ratioof oxygen in the flowing gas is 1%˜30% when a temperature is within1400° C.˜800° C., and the volume ratio of oxygen in the flowing gas is0.001%˜20% when the temperature is lower than 800° C.
 18. The method ofclaim 4, wherein a volume ratio of oxygen in the following gas is0.001%˜10% in an initial stage of the crystal growth.